I am new to this so I am trying to gather opinions.

I have the option of buying a 2002 Wrx Body with no engine for 1000.  And have found an STI engine for 3000.  Is it very difficult to install/maintain this combination? Can the wrx body, axels and all, handle the power of the STI engine?  will i need to replace a lot of stuff to install, or buy kits to install the engine?

the engine comes with complete headblock,5speed Transmission,Harness,Ecu,Top Mount Intercooler,Turbo,A/C Compressor,Alternator,Intake Manifold,Power Steering Pump,Coil Packs Starter,Throttle Body,Exhaust Manifold,Fuel Rail Injectors, Turbo Manifold(s)...

help please! any advice will be beneficial  

Depending on the year of your STI tranny, will depend on the amount of work that needs to be done.  These swaps have been done numerous times and usually entails the need to replace the hubs, axels, drive shaft, shifter, brakes...etc.  
www.nasioc.com <--would be a better place do do your research.