Thats correct, Tri, a loadable commodity in the hangar, only available to appropriate vehicles when selected.
Bombers are definitely a reasonable place to start...the slower speeds and long distances give you a little time to think.
Use auto takeoff (even the bestest will often leave it on) for simplicity's sake. Try to judge fuel load based on your round trip distance...don;t always haul several tons of unneeded fule around by always loading 100%. Kills climbout rate, too.
I'm a bigtime buffer, and usually like 10-15K, with 15 being sort of a standard. You still get very good precision (we have no wind drift or real big dispersal factors), but few pilots will have the patience to come up and attack, and if they do...they are usually too impatient to set up the attack correctly, and end up slow and hanging on your six...which equals dead meat!
I wouldn't bother with anything over 25K, as it simply past the point of effective returns(almost no enemy), although it can be fun to try once or twice, for kicks.
You're correct on your citation of hit percentages, and dropping the altitude drastically improved results. The overall package of strategic and tactical changes to bombing were a huge part of what made Curtis LeMay such a big impact on US strategic bomber command. Of course, when you come down lower, you'll get jumped more frequently. There's always a price...
Would be glad to help out anytime...provided you're a Knight. If you got your citizenship papers from somewhere over on the dark side (rook or bish), you're SOL, pal...
Seriously, hope you enjoy it!