Input? I'm guessing you're part of a payware group. Ok, here goes....
As far as aircraft and usage patterns... Usage, about the same as FS9 which I haven't started up in months (it's become more of a parts bin as has CFS 2 & 3). Online multiplayer most nights with the guys (using FS Host instead of the Steam servers), our racing stuff here and checking out paints I'm working on. Right new we've got a race on in the SW Pacific and I'm using the old AH Seafire III that's been reworked for FSX. Fun stuff.
Aircraft, mostly propliners and military stuff. Some of my old favorites have survived being ported over some have not for various reasons. Some payware that I'd bought for FS9 that came with a FSX version didn't fare well either. And some have. Both the Virtavia ones work great (F4D Skyray and the Gee Bees). The FSD Cessna 337 while it seems to fly fine has some panel issues that I haven't taken the time to resolve. But that one was always somewhat problematic with the panel. It's just really showing it's age in X. Lately, I've been more into early jets. Mostly the old straight wing ones.
As much as I enjoyed aircraft carrier stuff in FS9, I haven't picked it back up in FSX yet. I intend to, just haven't got there yet. I've still got a lot of old FS9 favorites to muck about with. But I have bought a few payware planes explicitly for FSX. Vertito SBD and the Aeroplane Heaven B-17F. The AH L10 Electra is going to be a must buy as well.
Aircraft failures. I'm iffy on those. I'm usually fine with them if they're not too intrusive. Keep the engines out of the red type things. I'm more of a kick the tires and go type though. If I have to jump through a bunch of hoops to start one up and fly it, it's probably not going to get much usage if it's even purchased.
Mostly my viewpoint on purchasing payware aircraft for FSX SE is that if it says it's for FSX Acceleration, I'll give it a try. From my understanding, they're close enough that it should work. However, if the price tag is over $30, then it had better state that it's for FSX Steam Edition. Under about $25, I'm willing to take a chance on. But so far in my experience, if it says Acceleration, then it's worked like it should in SE. With the old FS9 payware, my quick rule of thumb is to see if it has VC textures. Some do and some don't.