I used hot glue and just glued them in without gluing the top of the lenses in place. They sit back a little from the faceplate (but you can't tell) and it gives a little ventilation to help with fogging.
Short of knowing the makers for the various parts, it looks pretty good. I'd get a full breakdown of the components before bidding. And an unpainted jet pack will run $2xx-$3xx, tack on another $200-$400+ if you're not doing the painting yourself.
The teeth look good. Looks like you still have some plastic to trim around the eyes. You can see it in the top of the eyes in the second picture. Some of the movie used buckets were really trimmed out, I think you'll have to tape up the rest of the helmet to get a sense of what kind of eyes you want.
Did you use coat hangers to make the hand? Looks pretty creative. Most people start by assembling the biceps and forearms. They're straightforward and don't require as much trimming and shaping as the legs sometimes do.
A quick google search suggests the melting points of ABS and HIPS is above 140F, closer to 185-220. Still, if given a choice, I would find a cooler place to store the armor.