I still don't know why you are having issue with ActiveSync, everything is ok on my end and almost all users except you two don't have the issue. Try following Vin's directions
here. If that doesn't work, and a soft reset of both PC and Phone at the same time doesn't work, I really don't know, cuz I haven't had any issues with Active Sync (On XP, and Win 7 32 and 64 bit, I left Vista cold and hungry at the door when Win 7 hit the first beta).
Yes, tethering safe and always has been (and I don't think that even matters for Sprint anymore since they have unlimited data, as that's what your carrier lists in your profile).
Also, sorry for the delay in ROMs, ended up getting a bunch of extra work plopped on me this weekend.