will take forever to dry
no
yes yes
No, It is a nail hardener.
nail polish remover
This depends on the type of paint. You will have to follow those directions. The colour coat I used recently does not use thinner. The clear coat used 25% thinner and 25% hardener.
with your hands!
No, it must be wiped off with the appropriate solvent, preferably straight away. It will never cure without the hardener.
That would depend on what type of auto paint. With base coat on most brands, the drying time is controlled by which solvent you use to thin the paint. With acrylic enamel it's drying time is controlled with solvent and a hardener.
Ïf you don't use base coat the top might either not stick properly, or it might not cover properly. If you put the base coat on the top coat you won't get the gloss and maybe not even the color that you intended.
If the base coat used in your project is water base then yes, you bet you can. If there is any chance that the base coat used was an oil base paint then you cannot paint directly over it. The acrylic enamel will not adhere to the oil base paint and will begin to peel off as soon as it is dry. In which case a coat of primer is in order.
Clear coat is applied over a base color for the gloss
Yeah but it wont be as shiny...