VST/AU Export Question

[syntheticillusion]

Hello I am looking to buy a MAC secondhand for using Logic and Sonic Birth,
My question is what am i looking for in a mac, can you guy export a basic
VST for windows, like a bass or brass preset and make it a windows VST?
and can someone export an example with a brass vst, use datafilehost
so i can see what the vst's look like in windows, what do i need for
a mac, is a APPLE iMAC G4 duo-core from 2006 good? what do i need
to run MAC OSX 10.8 ??? I would like to make the switch to mac soon
I think I won't stop using windows but use both Mac and Windows,
I have bought a lot of synth and effects for windows that came with
Mac versions, so i already have some software for mac but i want
to mainly make presets and build VST's in Sonic Birth for Windows
so I can use them in my main DAW which is FL Studio, my friend
Steve uses something called Parallel to use windows software
on his mac so maybe i could use this software like synthedit and
synthmaker for exporting VST plugins? is this possible and can
someone export a synth with a single brass preset for me, so
i can see how they run on windows and what the gui looks like
if things go well i can buy a mac second hand and have this app
to make vst's for my pc and laptop computers and when i get
synthedit and synthmaker to export AU/VST's for MAC OSX then
I will give away many VST's I make on weekends and nights that
I want to be creative, I usually just design new presets for my music
or make a melody or two, so now I want to buy synthedit and maize
sampler and flowstone to make VST's and this app sonic birth when it's
commercial, I will do my best, right now I just have my VST plugins
but I want to buy a mac exclusively for this program and I was wondering
what do i need in a mac, because my friend steve said if you do buy a mac
buy one with a intel processor chip, can someone help me with these
questions on export and compatibilities and a new mac?