Welcome to the forum, fullmetalguitar.
Yes, GTP4 does support VST instruments, such as EZ Drummer.
And while GTP4 is a decent program, I might suggest looking at X1 Essentials.
The screen format for GTP4 was shared by Home Studio7 and Music Creator5.
It was abandoned after one generation for the other products.
You can download X1 Essentials. As a registered customer, it would be $79 for you.
The GTP4 upgrade would be $59, and it has to be shipped.
Either way, you gain quite a bit over GTP3, but I think X1 Essentials offers a lot more bang for your buck.