Vst 101 Help! Options

[sdpinc]

OK so I am o old school electronic musician looking to get into what is going on these days. I’m very used to rack mounted modules (Emu, Akai) and so on and running sequences through midi from a Macintosh based sequencer. I am really interested in learning on how VST’s work, you know the virtual instrument. I love vintage keyboards, but because of the cost of some of them, VST’s seem a much better idea. I wonder if someone can help me out with the understanding of them and how they work. Basically what I want to do is get a midi keyboard, use one of my Mac minis and then load it up with VST’s so I can use the different instruments like Nord’s and Moog’s and so on. Is this possible? Like to basically use the Mac as brain of the instruments, the VST’s as the sound banks and hook it up via midi to a keyboard so I basically turn the whole thing into the instrument, into I guess a software based synth? Is this basically right and if not can anyone help me get started? Any insight or help would be great! Another question I have about VST’s is in regards to running them. Can they run stand alone or do they have to be run through another program? If anyone could point me in the right direction here it would be much appreciated, I am really in a jam here and need some new sounds.
Thanks in advance
M.
Sdpinc@comcast.net