For one thing i would avoid all things ebay when buying an engine. Just no guarantees. Plus you have no opportunity to see it before buying it, or doing a compression check on it. But seriously avoid ebay. And make sure to get a clip. Engine sets have a lot higher risk of not working too well or have things missing. For one thing almost all engine sets don't come with the ignitor chip. Which is around 100 dollars or so. I got my clip from Venus Auto in Sacramento, California. So i'm not too familiar with other places, but I'm sure there's plenty of people on here that know places. As for the wiring you can find out the info here
http://www.frsport.com/sr20det....html
Or if you want somebody else to do it you can send your harness in and have somebody else do it. Also your going to need power steering lines and etc. There's a lot of topics on here about what exactly you'll need to do the swap.