Apologies if all the below seems really patronizing, but are you basically asking about the whole "philosophy" of control architectures? I think you are but if I'm wrong all this nattering is going to be annoying as heck...
Not sure if this helps, but think of any analog control as having a range, while a digital control has only "on" or "off". An analog ministick, main stick axis, brake lever, etc. will know where it is along the range of travel. Digital won't.
You can use a digital control to change an analog axis position, e.g. when "on" it's adding increments as long as the "on" is held. That's keyboard W-A-S-D movement. But the 'rate' of change is purely controlled by the repeat signal. Possibly some games might program in acceleration the longer the signal is received, much like your mouse's position changing can in Windows. Analog ranges of values can also have curves, alter how much deflection translates to how much 'change' you're desiring, or to what position "along the curve" is reported.
I don't know what control arrangement you've selected for your MCG-U, so will just talk default. Refer to the rightmost diagram here, it's old but accurate for the as-shipped config:
Anything with 'analog' in the name is truly an analog control, physically. The top center hat is an analog control, but (by default) configured in 'relative' mode so moving it to a position is providing a 'delta' to the X or Y (or both) values it outputs, and releasing leaves that final value reported. A light tap of center "zeros" axes back out. In alternate hat mode (long press to swap) the different positions are like digital button presses in a POV: up, up-left, left, left-down, down, down-right, right, right-up. But to the finger you won't "feel" it clicking discretely, so you may or may not like that for actual digital assignments. In the same way any analog axis can "become" a button but it might take the game a little while to recognize (e.g. you have to hit some threshold value or time of the value changing before it says "oh, he pressed it".
The bottom left is purely analog only, with a press. All other hats are up-down-left-right-center 5-ways. Brake axis is an analog range, as are main stick X and Y.
The flip-up trigger is a bit of a weird one. In electronic terms its purely analog with a range of values, I'm pretty sure. But the physical design of it (the way the detente works that you have to snap out of first to get it moving, and the way it locks in at the far end) make it feel kind of more digital, but with options for button assignments "along" the range between the two lock-in feeling points. By default I think it just has a button pressed when 'up' and nothing pressed when 'down but not squeezed, then another actual digital button that gets clicked if you do squeeze in the down position, but there are others (Safe, arm...) you can turn on in the software along the travelling-up range.
Now install if you haven't already and use VKB Joytest. Take a look at the sliders and how they react as you move the different axes. This both shows you their names, and their senstivities. When you look at VKBDevCfg for the first time, you'll be able to see that not all of them are using the same curve or multipliers. I believe by default the ministick (lower left) was on a 2x while the main axes were linear or something (don't hold me to that exactly, didn't re-check).
Anyway, now think thru your actual in-game functions you want assigned (mapped, bound) to some physical behavior. Things that are strictly "discrete" like a trigger, radio or radar on off, deploy / retract gear (assuming you don't want to emulate "cranking them down" somehow hah), push-to-talk on a microphone.... are better with digital physical feedback. Movements, aiming, etc. better analog. Something like a radio "squelch" control or volume range, analog. I don't play IL2 so have zero experience there, but hopefully you get the gist now. Just ...stupid as it sounds... "find your favorites" I guess. EXPECT it to take several tries to map many, many controls in a way that feels natural to you and makes sense. Think about grouping similar controls in the same hat. Think about things you need to do at the same time NOT both relying on the same finger (e.g. thumb) on different hats. Use mapping cheatsheets and pencil in as you go and erase and re-do if you find in the heat of the moment you're inclining to a different button, or that two functions you needed to toggle almost together were too far apart.
Here's an old cheatsheet I created for the MCG-Pro which matches the Ultimate (physically!) in default shipping config that you can print and write on. The tiny numbers will not match the actual "logical button numbers" for the Ultimate, but this is for writing in your mapped choices and feeling your way around, so you can ignore that or update them if you desire. The 2nd page shows a (much much outdated) example of how I mapped actual functions in Elite Dangerous.
https://1drv.ms/p/s!AuHD2NL7qn3wtTOuQgD ... q?e=m6YfJa You can even see where I added some of the "TEMPO" long/short press options to buttons, mentioned next.
Only after you get pretty far along here should you start to look at what else the software can do (in my opinion). For example the "Tempo" option lets you stack two different outputs on the same digital button press, one long, one short. (So the "long" is only triggered after say holding for 300msec or something, so very slightly delayed. But for example if you wanted to fire off chaff and flares you could make one long, one short on the same button. OR - you could assign a macro to the same button that when physically just clicked triggers "logical button press N, then logical button press M". You might like where you've mapped something but want to change its sensitivity, for example if you chose to use the lower-left analog hat to "look around" the cockpit, because when you release it you automatically look just dead forward again, but you want to be able to turn your head faster, so you'd increase the curve or multiplier (either in game, or in the VKBDevcfg software which changes the way the ministick reports analog values for ANY game).
Was I offbase of what sorts of things you were asking, and totally wasting your time with the Wall Of Text(TM)?
RH VKB GF Mk III + Modern Combat Grip *ULTIMATE* (12/17 GFII , upgraded), _powered_ deploy!
LH VKB GF Mk III + Kosmosima Prem (02/19 GFII, upgraded), *lateral* mounted
Feet: Slaw Viper RX Pedals [Sorry, VKB, too gorgeous]