1: Those armours don't give -dexterity. They set a certain amount of dexterity it allows. For example, a medieval plater armour has less movement space then a leather light armour.
it's worth pumping. Strength, Constitution and Dex are your stats as an melee basher.
2: I have no frickin idea. Only that Wookie's culturally despise armours or something. Plus, there are size issues.
3: They are found. Some merchants will sell them. You'll want to go for crystals too though.
If you walk up to a workbench and 'tune' your saber, you can select a slot (In k1, the 3 crystal slots). Doing so, you see a screen of possible upgrades. Selecting the one you want will place it in the saber, removing the already installed one back into your inventory.
4: Can't automate. It's not smart too. You'll want to use other attacks now and then.
But indeed, it's the strongest move. In numbers, then.
Immunity: Never really bothered. I'm not old enough to be familiar with the complete D&D rule set.
Saves: same, really.
Just remember there are dices behind EVERY ACTION.
2d4 are 2 dices that go up yo 4, maximum throw is 8, minimum is 2.
Hope this helps a bit. Some of the more expert member can help you with the saves and immunity bit