Do you have to use the setting powder for this product?

You don't *have* to use a setting powder but it lasts all day without rubbing off on anything if you do. I always use a setting powder and it works great.

Is this product good for the face?

Yes this product is just as good on the face as well as anywhere else on the body… please note that it's important to match your skin tone as close as possible when doing this due to the fact that our faces are sometimes different colors then the rest of our body so keep that in mind

Does is cover scars well like keloid scars?

I have no experience with Keloid scars, but I do know it should cover the "colored" part of the scar. It takes a little practice to get it just right so it does not rub off during the day. Worth experimenting - if you go to large department store like Macy's they will usually apply it for you and help choose the right color, if it doesn't work they usually will take it back if you purchased it. Good Luck..........

Would you recommend using this product to cover varicose veins?

Dermablend is a great product..you could use the quick fix body coverage for smaller areas.... but i would also recommend the "Leg and body cover" if you wanted to use on thighs and calf areas,hope this helps.