I run two live forums right now, a webstore and a few other things (some testing). I've been creating a new cpanel user for most of my forums to keep things separate. Is this your practice? Is is better to keep things separate?
Same thing I do. The biggest issue is when you don't do that, and you sell an asset things can get tricky, especially if the purchaser wants to export using cPanel backups. Stick with it, no harm!
Bigger sites have a seperate cPanel account for easy moving to new servers and such. All my 'junk' domains. Domains that I'm not really doing anything with right now are all piled in one account.