Yet, I or Yet I,?
Neither is grammatically incorrect. (Well, the first one should have of where the second one does, but I'm assuming that's not what you're asking about.)
A lot of punctuation is optional. Depending on whether you use a lot or a little of it, you can be said to have a heavy or light punctuation style. But even people who have relatively heavy punctuation styles rarely insert every possible optional comma at the same time.
In your example, you have two sets of optional commas.
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First, you set off and my peers with a pair of commas:
Yet I, and my peers, have lots of things ...
You can use both of these commas or neither. (You can't use just one.)
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Second, you set off yet with a comma:
Yet, I and my peers have lots of things ...
You can use this comma, or not.
Using both sets of optional commas together in such close proximity would be unusually heavy stylistically. Most people wouldn't do it, though you can if you like.
As an aside, your examples arguably violate the "X and I" constraint described in Thomas Grano's 1996 thesis. In section 8.2.1, he outlines an exception to this constraint "when the other conjunct is in some sense inherently secondary in the discourse" (p.41), but it's difficult for me to judge whether this applies (and whether or not the presence of commas affects the judgment). So, I'll refrain from judgment on this point and simply leave a reference to the paper.
They're both grammatical, because they both contain the same words in the same order. I expect you're asking about the punctuation. In that case, no commas at all are needed.
This isn't exactly a matter of grammar either, but writers often think it's polite to refer to themselves second, so my peers and I . . .