And my last question: should my entire civ have same religion?

[stormwriter]

I can't figure out all this religion, missionary, monstary, converting, state religion type stuff. I have the strategy guide, but i haven't read it as much, cause i'm too busy playing the game!
My main question, is whether i should try and make every city in my civ the same religion? Cause as it stands, i could care less about what city is what religion.

[Dominae]

Check out the Religion column in the Civics screen.

Most of the advantages you get from those relate directly to your choice of State Religion.

If your State Religion is Islam but many of your cities are not Islam (but, say, Buddhist instead), you will not get full benefit from Religion Civics.

[Dominae]

So, to answer your question (which I forgot to do in my earlier post!): yes, you should aim to have your State Religion in all your cities.

Note that there are benefits to having more than one Religion on each city: for example, a city with 2 Religions can build a Temple of each.