This is better than some books i read

still going through it but some questions.
Assumption:
1)Writing OTM calls/puts (range example: SPX price:1476, call 1550, put 1395)
2)Writing only with 30 days or less till expiration
3)Writing SPX only
Question:
1) What's the point of writing credit spread instead of just shorting naked calls/puts? other than to satisfy margin requirements
2) Why not write a condor instead of just writing a call or put spread? Then you can pickup extra nickels from both sides.
3) Related to previous questions, which is the better trade to write & why?
SPX current price at 1476
A) condor: $455 per contract
Sell -1 SPX JAN 2008 1550 Call (.SXMAJ)
Buy 1 SPX JAN 2008 1570 Call (.SXMAN)
Sell -1 SPX JAN 2008 1395 Put (.SXYMS)
Buy 1 SPX JAN 2008 1350 Put (.SXYMJ)
B) strangle: $810 per contract
Sell -1 SPX JAN 2008 1550 Call (.SXMAJ)
Sell -1 SPX JAN 2008 1395 Put (.SXYMS)
c) spread
Sell -1 SPX JAN 2008 1550 Call (.SXMAJ)
Buy 1 SPX JAN 2008 1570 Call (.SXMAN)
thanks!