Beautiful bunch of questions!
I'll answer your 32 questions so they fit all 30 caliber rifle shooters also, as the same bullet only a few thousandths smaller applies for it. In fact your guns need a .313 bullet diameter, which will work great in most 30 cal rifles without sizing down. Just seat deep enough so it will chamber easily, and size only if the case neck is too fat to chamber.
The bullet choice for your 32's is the 115 gr FN, which comes out real close to 120 gr when gas checked. Since you imply that you'll want a lot of bullets, for light loads, get a 4 cavity mold, and request one cavity gas checked and three plain base. Use the gas checked bullets for high velocities and low velocties if you should encounter an old gun with a bore so pitted that the LbT Lap Kit will not clean it up enough to handle PB. The plain base bullets will do fine in most guns at speeds to 1400 fps and possibly 1600 fps plus. If you leave the check off bullets cut for checks, for light loads, accuracy wil probably suffer in most of your guns, due to the short bearing length of this bullet.
For varmint use in rifles, which includes deer with your 7.62. Use Wheel weight alloy, water quenched and drive your bullets at not over 2200 fps if you don't want expansion. The results will be deadly beyond your imagination. Or drive them to the limit for the gun of interest, if you don't mind bullet breakdown and violent wounding with relitively shallow penetration. An example would be probably 2600 fps in a 308 - 30-06 or close to that in a 30-30, with good sustained accuracy with the barrel heated quite hot from rapid firing rates. (Only if LBT lube is used. Perhaps 2000 fps max for same results with most other lubes.) Or if you want expansion, air cool your bullets and take velocity to the accuracy ceiling for varmints, not over 2300 fps for large edible game.
For small edible game targets etc. -- !400 fps at the muzzle with this bullet will punch a little over 1/2 inch diameter holes through furred game, and be quite violent on feathered. If large bones aren't hit, i.e. shoulder joints, which will become a secondary projectile and very destructive. But that's the speed I like with this bullet, as it isn't difficult to keep most hits off the shoulder joint, and the power makes your rounds capable of taking large varmints and game up to deer very efficiently if the shot is placed precicely through the vitals. In other words, loaded to 1400 you have as near an all purpose load as it is possible to wring out of the batch of guns you are loading for. At the speeds I've described above I've obtained 1/2 inch accuracy at 50 yards from almost every rifle and revolver I've used, and some rifles will do it at 100 yards.
For target loads and even small game, this bullet will shoot with extreme accuracy at speeds down to well under 800 fps.
A 250 gr 41 magnum bullet, in LFN profile is excellent medicine for all big game, in rifle or handgun. It will feed and shoot well in the 41 mag Marlin as well as the 405. The same velocity specs, bullet hardness, velocities prescribed above apply for large game. I would use hard bullets and hold velocitiy at not over 1800 fps in the 405 for elk and such large animals if I were to carry this gun and bullet, to insure complete penetration. If air cooled bullets are used and driven at max or near max velocity, excessive expansion will reduce penetration more than I like for heavy game. Of coarse for small game, loaf them out at 800-900 fps to avoid excessive meat loss.
