Why not just get the correct BB, you have stated that this will solve your problems,

Also, the shifters you have, the SL-440's are from the Shimano road range, not MTB.

The front crank range which you have installed 50/40/24 is massive, can the FD even cope with this? a normal road triple is 30/39/50, that granny ring you have is real low for a hybrid, have you looked at a more appropriate cassette for your needs?