oldman-winter

I know next to nothing about engine swapping in Subarus. I am looking at a 1998 Impreza 2dr AWD and wonder what other Subaru engines can be readily swapped into this car. On Chevy's its easy because there is basically one engine bolt pattern and swapping is simple. What is it like with Subarus? Is there a guide to what will swap into what???? Also, about what does a Subaru 4cyl engine weigh? Does Subarus use a transaxle like a VW or is it a separate transmission and axle assembly? Can you readily swap manual and automatic transmissions?