The Net Bible note states that the phrase

"Is not Boaz our close relative, with whose female servants you were?” is an "idiomatic, negated rhetorical question...equivalent to an affirmation and has thus been translated in the affirmative" as "Now Boaz, with whose female servants you worked, is our close relative."  (NET Bible)

The introductory word regularly introduces a logical step in an argument, often a consequence or a conclusion; the particle

“falls back on the past and, making deductions from that, seeks to draw the consequences for the situation in the present or the future.”

"Our" is plural feminine genitive of "ego" in the Septuagint therefore translated "our" not "my", affirming Ruth's right of claim on TWO SEPARATE MOSAIC LAWS laws, one governing widowhood ( Dt 25:5 25:6) referred to as the "LAW OF LEVIRATE [brother-in-law] MARRIAGE" and a second governing the redemption of the property of one who was too poor to redeem it themselves & this involved the wonderful truth about the KINSMAN-REDEEMER (Lev 25:10, 13-16, 24-28).

The custom of Levirate marriage actually antedated the Mosaic law being seen as early as Ge 38 (Tamar seducing her father-in-law Judah because his sons had not fathered a son to perpetuate their dead brother's name & for failure to do so God killed them) viz., that if an Israelite who had been married died without children, it was the duty of his brother to marry the widow, that is to say, his sister-in-law, that he might establish his brother's name in Israel, by begetting a son through his sister-in-law, who should take the name of the deceased brother, that his name might not become extinct in Israel. This son was then the legal heir of the landed property of the deceased uncle (cf. Dt 25:5ff). These two institutions are not connected together in the Mosaic law; nevertheless it was a very natural thing to place the Levirate duty in connection with the right of redemption.

"Kinsman" (04130) (mowda'ath) means relative or kinsman. Without going into the grammatical details, note that in the original Hebrew sentence construction kinsman is given considerable stress by a reversal of normal sentence order.

Naomi may have interpreted Boaz's kindness to Ruth that allowed her to work alongside his maidservants as an indication of a favorable disposition on his part toward Ruth and possibly a willingness to do the kinsman's part.

Bertheau wrote that

"The modest man even in the middle of the night did not hesitate for a moment what it was his duty to do with regard to the young maiden (or rather woman) towards whom he felt already so strongly attached; he made his own personal inclinations subordinate to the traditional custom, and only when this permitted him to marry Ruth was he ready to do so. And not knowing whether she might not have to become the wife of the nearer goël, he was careful for her and her reputation, in order that he might hand her over unblemished to the man who had the undoubted right to claim her as his wife."

BEHOLD HE WINNOWS BARLEY:

"Behold" (02009) (hinneh) is an interjection demanding attention and could be translated something like "look!" "see!" Most often hinneh was used to point out people.

"He winnows" (02219) (zarah) conveys the basic thought of stirring up the air to produce a scattering and spreading effect.

Winnowing in Palestine consisted of throwing the mixture of straw, chaff, and grain up into the wind by means of a fork with large teeth. The worthless chaff was blown away from the winnower, the straw less far, while the valuable heavier kernels of grain fell back onto the threshing floor. The separation is the result of a breeze that usually blows off the Mediterranean from 4-5PM until sunset. The wind however must not be too strong, for then even the heavy valuable portions of the grain would be blown away with the lighter chaff. In summer the west wind blows very strongly in the afternoon but drops off in the evening, so that the evening hours provide the most desirable wind conditions. To best take advantage of this natural (divine providence) phenomenon the threshing floors were usually on elevated parcels ground with a hard packed surface.

And understanding of the typical threshing floor accentuates how fearful Gideon (who the angel of the LORD called a "valiant warrior" - see note Judges 6:12) must have been, for Scripture records that

"the angel of the LORD (OT manifestation of Jesus) came and sat under the oak that was in Ophrah...as...Gideon was beating out wheat in the wine press in order to save it from the Midianites." (see note Judges 6:11)

There is not much breeze in the lower elevation of the typical wine press! This was just fine with Gideon who did not want the exposure associated more elevated threshing floor.

"Barley"  (08184) (se'orah) actually means “a hairy or bristling thing” so called because of the rough and prickly beard covering the ears. In threshing, the grain was beaten out from the stalks with flails (cf. note Ruth 2:17) or was trodden over by oxen. Then in winnowing the grain was thrown in the air and the wind carried the chaff away. The grain was then removed from the threshing floor and placed in heaps to be sold or stored in granaries. Threshing and winnowing were a time of great festivity and rejoicing. Naomi knew (HOW DID NAOMI KNOW?) that Boaz was threshing his grain on the day that she had chosen for her plan. She also knew that Boaz would be sleeping near his grain that night, to protect it.

AT THE THRESHING FLOOR TONIGHT: 

The threshing floor (01637) itself was usually located outside town in a place where the prevailing west wind could be used to advantage.

The root meaning of the Hebrew word for “thresh” is “to trample,” which comes from this second threshing practice of using oxen to trample the grain. The people of Bethlehem took turns using the threshing floor. The floor was a flat hard area on a slightly raised platform or hill.  When the winnowing was done, the farmer normally stayed with the grain at night, camping out on the threshing floor to ensure that the harvest was not stolen. Winnowing (tossing grain into the air to finish separating the grain from the chaff) normally occurred in late afternoon when the Mediterranean winds prevailed. Sifting and bagging the grain would have carried over past dark and Boaz may have remained all night to guard the grain from theft.
 

Septuagint (LXX):  su de louse (2SFMI) kai aleipse (2SFMI) kai perithesein (2SFAI) ton himatismon sou epi seaute kai anabese (2SFMI) epi ton alo me gnoristho (2SAPS) to andri eos ou suntelesai (AAN) auton piein (AAN) kai phagein (AAN)

WASH YOURSELF AND ANOINT YOURSELF AND PUT ON YOUR BEST CLOTHES: (Mt 6:17)

"Wash" (07364) (rachats) is translated in the Greek Septuagint with louo which normally referred to bathing your entire body (Jn 3:10)

"Anoint yourself" (05480)  (cuk or suk) describes the ordinary physical process of anointing the body which in the ancient orient was usually with olive oil (Dt 28:40) particularly after bathing (2Sa 12:20) and especially for its fragrant effect. There were no supermarkets selling deodorants in those days. Thus in the hot Palestine climate olive oil or other ointment was used by the Jews to anoint themselves after bathing in order to give the skin and hair a smooth and comely appearance. It is interesting that the Jews had the custom of rubbing the head with oil or ointment at feasts in token of joy thus this verb is also used as a symbol of gladness. For example in 2 Samuel we read that

"Joab sent to Tekoa and brought a wise woman from there and said to her, "Please pretend to be a mourner, and put on mourning garments now, and do not anoint yourself with oil, but be like a woman who has been mourning for the dead many days." (2 Sa 14:2) In we read that provides "oil to make (one's) face shine." (NIV) (Ps104:15)

Solomon records in the context of verses on "happiness" and "joy" to "let not oil be lacking on your head (NLT paraphrases this latter as "with a dash of cologne"!)."  Note that Naomi did not tell her to make herself up like evil Jezebel who "painted her eyes" (2 Ki 9:30)

 From the NT, we know that anointing was a mark of hospitality for Jesus

"You did not anoint My head with oil, but she anointed My feet with perfume."  (Lk 7:46). 

Solomon records that 

"Oil and perfume make the heart glad, so a man's counsel is sweet to his friend," (Pr 27:9)