Primer/Sealant
#1

I've applied an even coat of primer/sealant to new drywall. Is a second coat needed before painting?
#2
No, not as long as there are no stains bleeding through, no second coat of primer is needed, however for best results I recomend 2 coats of paint. If the primer looks as if it could use another coat, kinda shady, that is normal, as long as you have it covered evenly.