I think I'll start off with a request for some tips for the first one, UFO Defense. I've got the power armor, I've got plasma rifles, I've got a tank, and I'm up against a bunch of sectoids in a terror mission.... They one shot everything. My tank rolls out, shot and dies, all my guys in power armor die in 1-2 shots, similar to the sectiods who aren't wearing any armor at all. One of my guys with a rocket launcher get taken control of, and manages to fire off 2 rockets. 1) When I have control of him his movement starts off at about 60% every turn and I can't even fire and reload it he same turn. Why can the aliens magically give him more movement? 2) The rockets hit 2 guys directly. They aren't hurt. Why do rockets not scratch my power armor, but I get one shotted?
Plasma weapons do humongous amounts of damage. Flying/power armour gives your troops a
chance to survive a hit from a plasma weaponry. They're still more likely to die than live, but out of a dozen operatives, few will survive a direct plasma hit. Rockets do little damage, but they do it to a large area, so they're good against weaker aliens, especially when there's lots of cover you want to demolish.
Just to reiterate: even the best armour is never guaranteed to save your individual guys, what they do is increase the survival rate of your entire team by a few operatives per mission. Never ever cook up a plan that relies on your guys taking a plasma shot (even from a pistol) and live. It won't work.
The reason your rocket guy is always out of TU's could also be because he's exhausted. If your soldiers carry more weight than they have strength points, they won't be able to use as many TU's per turn. I try to keep my rocket guys at ~40 strength, +30 at the very least, and have them carry nothing but a launcher and some rockets.
For reference, rocket launcher with four light rockets weigh a total of 34 units, most rookies have less than that from what I remember.And how do you guys get off the ship without being murdered by reaction fire? I send out a tank and if I feel like it, throw a smoke grenade before moving out.
Turn 1, prime and throw one or two smoke grenades near the skyranger exit. End turn. Turn two, charge out. Don't leave the ship before turn 2 because the aliens have full TU's on turn 1 and can thus reaction fire you to hell and back. Smokes work for other situations too. I always tend to bring one smoke per operative and use up most of them each mission. The concealment they offer is invaluable and has saved dozens of my operatives. Keep in mind that since this is an old game, there's only a limited amount of smoke that can be generated by the game. Keep that in mind when you throw smokes, grenades and blaster bombs.
How do you move around the map? I like to get into a house right away and slowly make my way around using cover and conserving movement points for reaction shots, but this is time consuming and not the best method in a terror mission.
How I do it: fire teams of 3-5 guys, each clearing out their assigned sectors (on an average farmland map, a huge barn or a number of smaller farmhouses make up a single sector). One guy is the designated scout, moving ahead of everyone else, preferrably with smoke concealment. The rest move up slowly behind him keeping enough TU's to launch several auto-/snapshot barrages at once when an alien is seen. As for terror missions, ignore the civilians. Take your time, keep your guys alive and advance steadily. Aliens and civies are spawned randomly and so whether or not the whole lot of them get killed or not is mostly down to luck.
Some personal observations on weapon effectiveness in veteran difficuly:
-Assault rifle/projectile weapons give a decent chance of one-shotting sectoids and floaters
-Laser rifle takes out all primary alien types before Mutons show up
-Heavy plasma works for everything
That said, I usually field a large number of laser rifles very late in the game. Of course a single LR won't kill a muton, but when I have three or four guys autoshotting with good accuracy, I get results.