Elemental Combat - How's it work?

Ok, I think I have the basics of combat, but there's lots of holes still and I prefer to understand the implications of my gear and unit decisions a bit more than I do. So here is what I've gathered together from playing and staring at posts here and reading the manual about how combat is supposed to work. It's possible that this is outdated, misinformed, or simply wrong. My intent here is to get a better handle on it, so any corrections or insights would be appreciated.

Anyway, this is what I've got:

For 1-on-1 fights, things don't look too complicated. There is no "to-hit" roll, so I just randomly deal damage between 1 and my attack value. Guy randomly defends damage between 1 and his defense value. If the guy has armor that is "better" against my attack type, he automatically gets max defense from relevant items instead of rolling for them. His defense is subtracted from my attack. If any is left over he takes it as damage. If it's 0 or less it counts as a miss.

Somewhere in here a dodge roll happens. Somehow. I honestly don't know how this works, just that it's in the game. If successful, guy takes 0 damage regardless of the rolls and I miss.

Attacking with a group unit is supposed to function similarly, except that you roll once for each individual in the group on the attack using their individual attack numbers instead of the big one that's shown. It is unclear whether these are compared against defense individually with only the remaining summed as damage, or if they are summed first and then compared against the defense roll to determine damage, but it looks like they are summed first. If they were summed second, we'd see a lot less armies of peasants with 1-4 weapons dealing substantial damage to anything with a 8 or better defense.

I don't even have a clue how defending with a group works. Assuming that attacks are summed before comparing, it's unclear whether they roll a defense for each member and sum it up or just make one roll where the max number is the sum of the individual defenses.

Group on group combat doesn't appear to have any extra rules floating around, and is just more of the summing and comparing.

I'd appreciate any insight into this process that's floating around.