To add to what Tiresias said, most vehicles currently have a requisition tax associated with them and repairing vehicles with a builder will probably drain you dry while they are being worked on. I find it a good idea to build a good infantry army first (maybe with light vehicle support) if you can get away with it.
For Chaos, I’ve never noticed the vehicle cap growing as I capture/LP more points, and I just ran two tests on two different large maps with a lot of points.
For all the special units per mark (i.e. obliterators) it would be nice to have a commander icon at the top for them as well as the chaos lord or sorceror. Edit: I reconsidered how I wrote the above and just wanted to make a note that I really mean for units that are late tier and limited to one. However, I understand that you all have a lot on your plate right now (both in life and working on the mod) and I don’t know your plans for Chaos. Therefore, I will just fling a suggestion at you every now and again, not really expecting anything in return.
On that note, I love the obliterators (the new sounds show the weapon switching nicely), and the plague marines are very cool (even if I have to micro them away from my own men). I also am interested in the marks in general, and can’t wait to see what all you’re planning to do with them.