Alright, so I will have Modernbill and Plesk 7 on my server. Now, I need to set everything up before any clients make a purchase. I need to know if I ONLY use Modernbill. Does it automatically create everything on Plesk. Ex. accounts, limits etc.

Or do I need to do this on both. thanks.

it will do it for you, as long as you have it configured properly. i havn't manually set up an account in PLESK since i got modernbill.