2. Better, but if you want something out of personal taste, just pick one.
3. Actually, unless you're going to use the mail in rebate which no one does, you only save less than 5$.
4. If you really want to get the 4590 go ahead. But if I'm not mistaken you'll get 1-3% better performance over the 4460.
Looks good, and
1. No. No need to get anything better than the stock cooler if you're not overclocking.
2. If you want to be able to use CDs/DVDs.
Stock Coolers are quite loud though :/