tax treatment of closing costs

What are the tax consequences for the following 100% residential rental situations?

1. seller paid closing costs
2. buyer paid closing costs
3. buyer tacks the closing costs onto his mortgage
4. what is the better scenario? having the seller pay $xxx or reducing the purchase price by that $xxx
5. what is a closing cost "rebate"

i assume for #1, the amount is capitalized (increases the tax basis) and depreciated over 27.5 years.