Flock, Herd, Cattle: Animals in Eclogues II

This week I would like to (partially) devote my attention to pecus:  

pecus, -oris, n: a flock or herd, freq.; cattle
pecus, -udis, f: one animal of a flock or herd: an animal, a sheep

pecus, -us/-udis, m: a head of small cattle, one of a flock; a sheep

    Going through the first two Eclogues, I thought the only way to make a distinction between flock/herd/cattle, was through context.  Then I noticed their forms.  Please forgive me if this is obvious, it was a revelation for me...  Although all three words can mean flock/herd, in Eclogues I, II and III, it seems Virgil uses the neuter form in the singular when describing a flock of sheep or goats, as well as a single sheep:  

quam dives pecoris   (Eclogue II.20)

how rich in flocks

pecoris, n, gen., sing.

ite meae felix quandam pecus ite capellae   (Eclogue I.75)

Go, once happy flock, go my little goats

dic mihi Damoeta cuium pecus an Meliboei?   (Eclogue III.1)

Tell me, Damoetas of who is this flock, of Meliboeus?

pecus, n?, nom., sing.

et sucus pecori et lac subducitur agnis   (Eclogue III.6)

both the juice is taken from the sheep and milk from the lamb 

pecori, n, dat., sing.

But, uses the feminine plural when referring to a group of cattle:

nunc etiam pecudes umbras et frigora captant   (Eclogue II.8)

still now my cattle seek the cool and shade

pecudes, f, nom., pl.

    Sometimes when describing herds of sheep/goat Virgil uses the term grex (gregis, m) (Eclogue II.30; Eclogue III.32).  I assume the choice between his use of grex or pecus lies within meter....

Now that my mind is swimming with flocks of goats and herds of cattle, I looked to Theocritus for guidance but was met with more questions.  Eclogue III borrows the first line of Theocritus' Idyll 4: "Tell me, Corydon, whose cows are these? Do they belong to Philondas?". Theocritus makes clear which species of animal using the Greek αἱ βόες (fem., nom., pl.) meaning cows,  Εἰπέ μοι, ὦ Κορύδων, τίνος αἱ βόες; ἦ ῥα Φιλώνδα (Idyll 4.1).  Thus, if Virgil models this particular line in Ecolgue III so closely, is my analysis of pecus completely unhinged?  Is he in fact referring to cattle and not the flock?

    In Greek, βοῦς can either be masculine or feminine depending on the, well, author, and what they are referring to-- ox or cow.  When referring to oxen, rather than using the masculine, pecus, Virgil uses the term iuvencus (-i, m) meaning a "bullock" a.k.a. ox (yes, I had to google bullock) or young man-- I am sure this has to do with meter as well...

aspice aratra iugo referunt suspensa iuvenci     (Eclogue II.66)

look, the oxen bring back the plough having been hung from the yoke

To end, how does one yoke an ox?  Every time I read this line I just picture a dozen egg yokes dripping from the top of a cow's head.  That must be wrong.  In antiquity an ox, or cow, rarely an ass, but preferably an ox, would be yoked either from the horns or the neck using a piece of wood fitted to go over the oxen's horns, or fitted above the oxen's necks and secured by either leather straps or a U-shape lock that is inserted into the wood piece.  Did I do a terrible job of explaining that?  I am sure of it, so here is a video, albeit modern:

The plough would then be attached to the yoke, either from the middle:

(Thank you https://collection.sciencemuseumgroup.org.uk/objects/co38798/model-of-ancient-roman-plough-model-representation)

or from the sides:

Silver coin, Octavian, veiled and laureate, ploughing with yoke of oxen right, holding whip in left hand. (reverse) Head of Apollo, laureate, right. (obverse), 29BC-27BC, Minted in: Italy (Brundisium and Rome?), The British Museum, R.6171

The oxen pulled plough first appeared on coins in the Republic, usually with the bust of the goddess Ceres on the other side. This coin, however, was minted after Augustus founded the city of Nicopolis in honor of his victory at the Battle of Actium, so humble. It shows Augustus literally ploughing the foundation lines of the city. Holy cow, I digress... I believe we shall meet the plough again in Virgil's Georgics, so let this be our aperitif.