The burn rate is an odd thing, I agree. I can launch with %100 and 15 min later I still have 53min of fuel or more. Sure, the higher the B26 goes, like most planes, the better fuel efficiency it has. Ultimately, don't let the 53 mins of fuel fool you, can can go much further.
WEP? I didn't think the B26 had WEP in any case.
Bomb sights speed indicators worked for me yesterday. Did you have the sight aimed?