I replaced my pump this year. I can't answer about your sizing question, but I thought the actual wiring of the new pump was pretty simple. Basically 3 wires plus the bonding lug. There is something called an "impeller seal" that I struggled with getting in the front of it correctly; when that's got a problem it leaks. The impeller seal may be what's wrong with your existing pump as far as the leak (and they are only about 10 bucks).

The noise it's making; is it a ringing type sound or is it just a noisy motor? Mine had been making a very loud ringing noise; which I was told is generally caused by bad bearings. Couldn't find anyplace to replace the bearings so I replaced the whole pump. When I say it was loud, I was worried the neighbors were going to come beating on my door because of it.