That's the trouble with learning BMS is that the whole F4.0 to BMS evolution has meant an evolution in features and the documentaion is likewise piecemeal. Learning it from scratch is hard because the reading is a breadcrumb trail of upgrades and learning it having prior experience is problematic because you might think you know things that are no longer up to date (countermeasure system, for example).

As for controls I strongly suggest to everyone to map the HOTAS to their keyboard/controller themselves in a manner that is the most natural of the individual. Memorizing defaults is hard and unnatural. When the user chooses their keybinds familiarity and memorization are greatly enhanced. Often the trick (as when moving into a new house) is to reach for a desired item as if it was there already and then make that instinct a reality. Go to where you think the forks and spoons as if getting one out of the drawer should be and that's where you should unpack your forks and spoons. The sooner the user thinks in terms of DMS, TMS, uncage, etc. instead of backspace, ctrl-arrow, numpad_*, etc. the better. For everything other than HOTAS the cockpit is clickable.