30% backwind is no big deal. Add some halyard, add cunni, and live with it. 30% backwinded is fast, but much more than that, and it's added drag.
2.5 minutes a mile is a lot. Are you playing follow the leader still? Or are you splitting tacks w/ the ringer? How competative is your fleet?
And the more important thing than the main sail, is that you don't have a relationship with skipper that allows open conversation and critizism to help make the boat faster. For instance, I posted pictures online from a regatta where I couldn't point, 5 pages of specific suggestions later, the boats points great and we're racing a lot better.
Explain to him/her that you want to take some pics and post them on a sailing forum to help with your trim. Tell him it's to make you better (not b/c you think his sail is crap). Also, start to ask questions like "the sail looks pretty good, how old is it?" If he comes back with >5 years.... you know the reality he doesn't want to accept.
Boom and traveler relationship. Assuming a close hauled course, the boom should be on centerline. Trim so the tell tails all flow aft except for the top one. That should break about 50% of the time. After you get that, check the position of the boom! Is it on center? If not, move the traveler up to windward to put the boom on c/l. In lighter air the trav will be to windward most of the time. The sheet will be very eased. Moderate air the sheet will be hard on and the traveler will be centered. Heavy air, the traveler drops down below center as does the boom, losing pointing and adding drag from a luffing sail.
If the boom end 'sags' (points down instead of horizontal) no big deal. You see that a lot on boats.
Merit 25 # 764 "Audrey"