Hey all, just wanted to say my hello to the community and such, so Hello!

I also had a few questions about skill/stat points. I wasn't really sure if there were guides on it or not but thought I'd be safe to ask in here.

Are there specific skills I should avoid leveling up as a Commando or Engineer? Also what stats should I upgrade for a Commando and an Engineer?

On a totally unrelated note, can any of the items for the cash shop be traded?