I'm trying to gain a better understanding of the steps needed to get a custom character model in-game, both for units and walker vehicles.

After poking around, it seems like these are all the steps that need to be taken:
- Create geometry
- Envelope geometry to a skeleton
- This skeleton determines how the model is animated in-game

Have I missed anything? Are there other steps that I'm not aware of? Is there a difference in the process for units and that for walkers (aside from using a different skeleton)?

That's all. Maybe if you make a new walker/unit that is completly different from the stock you need a new animation set

For the character..That's actually all. But ingame he would look weird if you won't edit the weights I think. I got this bug as you can see in my latest 3d modeling/animation topic.

I think he mean the weighting with enveloping. weighting is a part of enveloping