the 3L forums are going to have a lot of the answers to your questions. I would actually recommend the NECO 3L forums (forums.fastcougar.com), as they have a whole load of FAQs on what you can use, what you can't, and how to do it.
The easist 3L swaps are the Escape motors. If you plan on a hybrid, then it really doesn't matter, 'cause you'll be using your heads on the 3L block. Either way, to do it right, you'll need some holes in the block filled (welded & resurfaced is the only way I'll do it), the pilot bearing cut (not pressed) out, Clevite rod bearings for longevity, and a good clutch/flywheel combo to hold the thing down. Plan on $3k for starters for a hybrid, plan less for a straight 3L swap, but a lot more time in the machine shop for fabrication (IAC, EGR, etc).
