hmmm... it's quite a common newbie issue but you might be trying to do too much in too small a case... see my signature and spend some time thinking about the contents of it - a few days at least...
saying that, pam's can do both envelopes and lfos and will be more than enough for now and I wouldn't worry too much about having enough vcas - just buy a good quad cascading one for now and see how you get on... by good I mean a mutable veils (or more likely a clone) or an intellijel quad vca
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities