Actually, PM is a board function. Though, it appears you have yours turned off - you can click on the little icon with an envelop and two figures in a post to PM that post's author. You can then exchange email addresses, etc. without leaving yourself wide open (security-wise).
The MT rules (I am just going through them) actually state the if you want to change careers, you should muster out, then begin role-playing. So, that would make chargen ... ummm ... over, at that point. I prefer the idea of allowing career moves - but only if explained well. (I think it is first mentioned in CT, Supp3.)