Two questions on preaching

[onomastikon]

I have the feeling that preaching doesnt seem to raise my dominion at all. Or at least I dont notice it. Does anyone know how it works exactly -- do I need to do it three turns in a row? Or a number of turns equal to the priest's level?

Maybe this is common knowledge, but I was experimenting: A sneaking sage in an independent province / enemy province cant search for magic sites, it apparently counts as an attack on the country (odd), but a sneaking priest CAN preach! But does this work the same way that preaching in your own province does (however that may be -- s. question 1)?

Btw, does having the "sneaky" symbol have any effect on the battlefield?

thank you