Does this product set eye make up as well?

Put mascara and some eyeliners on after you set your face makeup. It does help eyeshadow stay put longer.

Does this work well for very oily skin? For me, normal Colorstay makeup wipes off after 1-2 hrs, Dermablend after 4 hrs. How does this hold up?

I have VERY oily skin. I love this because it's inexpensive and seems to work just as well as the Urban Decay All Nighter. To use it, I apply primer (lotion kind) and fan it to dry. Then I spray this pretty lightly and dry it. THEN I put on my whole face EXCEPT mascara. I use concealer for my dark circles and to highlight and I set that with translucent powder. For contour, I use powder instead of dark concealer and that helps with the oiliness, too. I set my whole face with the Dermablend translucent powder then spray this on again, kinda heavy and fan it dry. Then I put on mascara and lashes. It definitely helps and it's affordable enough to be used generously.

Does it prevent transfer

To a point. If you rub your face on something it will transfer. I use it every day though because it helps a lot with helping it stay even with rubbing you will have makeup on your face it will just look a little patchy up close in that area.