Everything that effects enemies on the tactical layer

[Postmaster]

After playing some LW2, it seems like there are many factors that go into the strength of aliens in the tactical layer and I'm not sure how all the different things work together. I can identify the following factors that may be affecting the aliens you see on missions.

1. Infiltration level vis-a-vis the number of aliens (Extremely light, very light, etc). I understand this in that more infiltration -> less enemy numbers at certain cutoffs, but other benefits as well.

2. Readiness level (Vulnerable, normal, guarded, etc).

3. Advent strength level in the region.

4. Alien force level.

What I'm wondering is how all of the above things interact to dictate not only the number of aliens on a mission, but also the types of aliens, how big the pods may be, and the AI behavior on a mission (i.e. guarding the objective), and any effects they may also have on the strategy layer.

Thanks, big LW2 fan!