Two quick points:
1) If it were me, I'd bend on the new mainsail. You sound like you're far enough along the learning curve not to worry about abusing it.
2) The leeward shrouds should not be "very slack" as you indicated they are. Fine tuning the rig
takes experience and practice, but getting it gross tuned is not that hard. Definitely tighten those sloppy shrouds until they remain mostly taut even when they are on the leeward side (they will certainly loose some of their tension, but they should not be sloppy).
The assymetric pointing ability is most likely caused by incorrect tuning of the shrouds. Overall pointing ability may be due to a lot of different factors, but insufficient mast rake could be one.