First up, welcome to the hobby, the game, and these forums!
Yes, a Marcher Priest (a Friar, perhaps?) dedicated to Courage is a fine idea.
Please don’t hit people with books. Carry one around, by all means, and read from it (excellent idea, as you can then have sermons and speeches and setting notes in it), but don’t use it as a weapon. As noted above, even if you can find a larp-safe book, it’ll not be much use
The mechanical benefits of the priest skills are numerous, but subtle. For example, we’ve had skirmishes and battles with nasty overlaying emotional effects. Fear. Weakness. Incipient Madness… In these cases, those blessed (Anointed) could push through the problem and carry on regardless. Last battle had a nasty sort of wraith thingy placing curses on folk: They needed to be exorcised in 30 minutes or they died (allegedly). Hallowings and Consecrations I can’t speak of, but I suspect others can tell you of their use.
They are also fairly RP heavy. If you can lead people in a prayer, give a short call-and response, small sermon, that sort of thing, you’ll be fine. Usually your subject will be joining in and pushing it along as well.
If you’re jumping into LARP and Empire as a priest, for your first character, you’re really going for the deep end. To compare it to D&D: You don’t get to ask the referee if your character would know something. You don’t get a prep card from the DM of stuff that might come up this session. Your character knows only as much as you know.
I mean, we’re a nice bunch, and we won’t pull you up on any mistakes or blank pauses, but if you’re going to play a priest, you’d better have a pretty good grasp of the religeon. So yes, a book full of notes (including of all your abilities), several sermons to bellow during battle, and a big hammer makes a pretty good start.
Now, a quick note, you start play with 8 character points, but you don’t need to spend them all at once. You could quite easily go for
Dedication (huzzah, you’re a priest) for 2, Anointing (blessing folk with Courage) for 1, and leave it there for a little. Armour and ability to use a (1-handed) hammer comes free. I would also take Congregation as a personal Resource, allowing you to fuel you priest abilities. It also sells well.
And then, if you decide you want to take your character one way or another, you can drop in to the Games Operation Desk (aka GOD) and ask to adjust your character one way or another. For new players at their first event, they’re very forgiving, anyway.
For a spot of healing, Chirugeon works fine, but have you considered the Hero Skills? Hero Points and, say, Stay With Me would cost a total of 3 character points and allow you to bring someone from dying to 1 hit with a few seconds of roleplay…
Happy to answer further questions, including re background. Have you found the Facebook page for the Marchers yet?