Perhaps, but only if it didn't destroy the inventive to actually preach. I think that given the present difficulty for most religions to even get priests (How many religions have only 1 priest?) that making things harder then they already are to preach in other realms would pretty much kill it. In the 4 religions I've had priest in we already "couldn't" preach outside of "allowed" regions, on threat of being banned by our realm. Add in a simple button press to "combat" the few priest that do preach were they want to, and I can't see the practise surviving at all.
I really don't see either case as working to produce wars though, unless the religion is backed up by a realm. Most times I see this sort of thing, the realm just disowns the priest, since really why would they go to war over religion unless it is a theocracy or the ruler happens to share the religion. People SHOULD care that one of their nobles is arrested, but the dominant attitude tends to be, well he was preaching where he shouldn't.
Precisely. Priests were being arrested left and right, and nobody ever raised a fuss about it. It meant that religions has no means to cross borders, because they'd be arrested on sight and their realm would not defend them.
It not requires a lot more muscle to keep priests out, which is necessary for the priest game.
