What do you mean odd Zombie? It's Ivan, Fidel and Vicky. Vicky sounds the same, Fidel sounds the same, and Ivan is well Ivan... I also noticed that it's XCOM-ish, and I think it's good idea. Personally if I would to redo JA series I would do it that way but without all those special perks from XCOM(2)
Question about 5. I assume destroy all known alien colonies? So if you go to T'Leth but there are colonies that you don't know about is it fine? Could you provide the edited purchase.dat?
Vs MECs gunners with Bluescreen rounds or emp grenades. With luck they will go disabled, alternatively it will help support for hack. I'm not sure we are talking LW2 specifically, but Mutons you can lock down in LW2 with Shinobi/gunner with combatives - though it's not foolproof plan, but it should work 90% of time. Otherwise in standard campaign - anything that reduces their aim - flashabng, poison rounds, suppression.
At the beginning it's like I have flashbang on every person. It helps vs Sectoids, it helps clear overwatch and it helps with reducing AI accuracy. Until you have some other utilities that help with that and are more deadly. Smoke I use less often since it's only purpose is to help with defence, but when fighting vs snakes or sectoids it doesn't stop vs mind spin or poison spit.