What were the Choshen and the Eifod, respectively?
Rashi: The former was a kind of ornament that was worn next to the heart; the latter, a kind of apron (that was worn at the back from the waist down and) that had side-straps 1 which were tied in front as well as shoulder-straps that were affixed to it, one on either side of the Eifod. 2
Rashbam: The former is a kind of bag, 3 the latter, a kind of garment that one raps around oneself, and that is worn on top of one's clothes, both at the back and at the front.
A belt that was woven together with the Eifod - out of the same threads, witth pictures of Keruvim like the Eifod itself, that extended around the Kohen Gadol's waist and was tied in front (Rashi, Pasuk 7).
The Torah will provide more details of all eight Begadim in the course of the Parshah.
To house the Urim ve'Tumim, which will be described later in the Parshah.
What is the definition of "Kesones Tashbeitz"?
Rashi, Rashbam: Targum Onkelos and Targum Yonasan: It means a shirt with ornamental settings. 1
Which one generally makes in golden ornaments to house precious stones and pearls - as we find later by the Eifod (Pasuk 11 [Rashi]).
What was the basic difference between the Me'il and the Kutones?
Rashi: They are both a type of tunic (shirt) - both with sleeves, only the latter is an undershirt that is worn next to the skin, the former, on top of it. 1
Ramban (on Pasuk 31): The latter is a kind of tunic with sleeves, whereas the former is a cloak - without sleeves, that encircles the body; it is closed at the neck 2 and covers the entire body, but opens in front by means of two flaps. 3
What was the "Mitznefes"?
Rashi and Rashbam: The "Mitznefes" is a hat. 1
Ramban (on Pasuk 31): It is a turban measuring sixteen Amos, that wound round and round the Kohen Gadol's head, as opposed to the hat of the Kohen Hedyot, which was similarly woumd around the head, but spiralled upward. 2
And is synonymous with Migba'as - in Pasuk 40 (Rashi).
Which explains why the Torah sometines refers to the Kohen Hedyot's head-covering as Migba'as, though it refers to that of the Kohen Gadol as Mitznefes, exclusively. See also Rav Chavel's footnotes. Basically however, the Kutones, the Mitznefes and the Avneit of the Kohen Hedyot were the same as that of the Kohen Gadol (Ramban, Shemos 39:27-28).
Where exactly was it worn?
Rashi (on Pasuk 37): It was worn above the forehead, with space in between it and the Tzitz to don Tefilin.
What was the difference between the "Avneit" and the "belt of the Eifod"?
Rashi and Seforno: The former was to tie the Kutones, the latter, the Me'il.
Why did Hashem omit the pants and the Tzitz from the list?