Paint - Repairing Base Coat

Took the hood off my 69 Dart to paint it. Hung it vertically so I'd be able to paint both sides. Had two problems:
1) Got a couple of runs (on outer side, of course). Tried to repair it by scraping runs with razor blade and painting over it. It looks marginal. Should I just wait, sand, and repaint? How long should I wait before sanding?
2) Found a bullseye (sunken place) on top side that I just flat missed when block sanding. Tried building it up with paint (like with primer). Can this be done, or am I stuck with filling, sanding, etc., the traditional way?

If I build up the "bullseye" with paint, how long should I wait before sanding it each time?

If I decide to lay the hood flat and apply base/clear one side at a time, how long should I wait before turning it over to paint the other side?

tks...........jas