Help Me Paint My Guitar White!

[cosmic_osmo]

A few questions for an alder project I'm doing:

Do I need grain filler with alder or will sanding sealer work?

I'm painting it white. I have a can of flat white paint that looks good, and if I use this then I will finish it with nitro.

OR

I was considering using automotive paint, since that stuff is already nice and glossy looking.

How do you guys feel about using automotive paint on a guitar?

Also, if I do end up using the clear coat, will it make any difference if the paint underneath is "glossy" or "flat"? In the final appearance?

Thanks!