well.. you have to get an obd1 => obd2 conversion harness. just a seach for it online (i recommend the skunk2 one..my friend has it, and it works fine)

well.. it is better, but not for the price you'll pay for it

the compression ratio is a little higher (11:1 vs the stock 10:1)
different internal motor parts... but i'd just get a USDM engine, and spend the extra $$ on aftermarket internals.

hope that helps.. need more info, just post.