Hey welcome along!
The other guys have already covered it a bit:
Stock engines are NA (~220bhp) and Twin Turbo (~325bhp).
You get the following combinations:
JDM NA Auto
JDM NA 5spd Manual
JDM NA 6spd Manual (a bit rarer, from 96-02 only)
JDM TT Auto
JDM TT 6spd Manual
UK TT Auto
UK TT 6spd Manual
The UK spec models production ended in 96.
They started making the VVTI engines in late 97.
You will hear/see the term prefacelift and facelift often. This refers to the 93-96 cars (prefacelift) and 96-02 cars (facelift). There are some differences (facelift cars have grey surrounded rear lights, black inserts on the headlights, sidelights in different position, side repeaters in different position, different seats, different dash dial layout amongst other things) between the two.
A little bit of time spent here will get you acquainted with Supra specific stuff very quickly!
When it comes to single turbos (and big twin turbos), they are a whole different kettle of fish. These setups have come from aftermarket tuning and can give HUGE power. Usually an expensive route to take though!
How much are you looking to spend?