listen to the voices ... the little voices in ur head always are right.
on a serious note, Basicly the unwritten rule is that u follow the first commands given.
no difference between type or chat.
Overall most people don't pay much attention to what's typed while playing pb, so chances are most people won't even notice the typed parts anyway (unless they're being spammed).
If it happens to be that there are contradicting orders, u have to get things straight as soon as possible. and make sure everyting is clear. (the mic has a benefit on this part). after that u can clear things out.
In your situation, make sure things are stated clearly. if there is any type of confusion tell them straight what to do first (keep it short & fast). so u keep control & then clear out with the other guy what will happen next.
Personally i prefer that 1 person is telling the group what to do. this way everything stays clear. and accidentaly 'rebels' will be prevented.