Thats correct, as it stands right now there is no mixing for the most part. But armies have to come from one list.
http://warzonegame.com/images/the_corpo ... l_v1.0.pdf Heres the Imperial pdf, download it and give it a go through. If you decide to go that route, I suggest getting 2 starters to begin. That will give you 2 big squads of Trenchers, the rank and file troops, each with a NCO. It will also give you 2 officers that will act as custom character potential, 1 as a warlord and 1 as a lord. That will also give a pair of Greyhound LAFVs, baby tanks that can fill gaps as needed.
Effectively, the foundation of an army. After that, consider the Blood Berets and the Golden Lions. The Hurricane walker is also a fantastic looking piece and should be a blast on the table. If you couldn't tell, Imperial is going to be army number 3. Heres my shopping list.
2x Starters
2x Blood Berets
2x Golden Lions
1x Hurricane
1x Rist
Anything else I can help with, please ask.