Sorry for reviving this thread, but I thought I could give some input also.
To 1): I think that wouldn't be very useful to the game and logic itself. Of course, the aliens & the UFO would be devastated but at what expense? Rather your soldiers would fight to death than to blow the place up without a battle, at least that's what I'm thinking.
To 2): Hm maybe a idea to save staff and could make sense, but I doubt too many players would use it. I'll just leave this decision to the coder-staff
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To 3): I agree, nice idea. But as I see it there should be a certain system to do it, maybe place some traps you have built/bought before the battle in the first round before PHALANX/The aliens move. To think this a bit further, regardless of the types of the traps there should prolly be a limit of useable traps or a expected failure rate... the traps could make a base defense mission a bit too easy.
To 4): Reminds me a bit of Ufo: Aftershock or what it was named. Hmm I don't know if this would be good in the campaign for Ufo:AI but something to keep in mind.
To 5): When I think back to Ufo: Enemy Unknown some of their missions already were Kamikaze missions
. I'm not too fond with that idea, just too less excitement.