Uh, there may be an obvious answer to this but I'm a new player to the series so I cant be too sure.

If I send my companions out in parties and they're raiding villages and attacking bandits and what not.. I'd want them to be good at fighting right?

But, what if I send a surgeon out in a party, who is great with meds but not great at fighting? Would it be better to keep her with my party so she can heal my troops, or does it matter?

I'm in a war right now, so it makes sense to me to just get a bunch of companions that are fantastic fighters and send them all out on parties. But that just seems to easy.

And, using the surgeon example again, if I send her out in a party, I'm assuming I no longer have the benefit of her healing my troops correct? I lose that bonus?

The game does a terrible job at explaining things.