1. Skills remain that way, yes. You get 3 Skill Points to allocate at 120 upon advance though.
2. Angel Ray is your main attacking skill, however 2 issues arise. 1) Angel Ray 10 is only available from Zakum, which requires you to do prequests. 2) You're a Bishop. They're purely support now.
Most Bishops I see don't have Angel Ray as they're support, and Big Bang is pretty good as an attack for them. Advanced Blessing will be your main asset as a Bishop, as well as Holy Symbol. I won't say a skill build though, as I've not made a Bishop. I would however put 1 point into Big Bang as it is an amazing level 1 skill.
3. LHC will most likely be your main area till later on in 14X or 15X. I still go there at 155 as it's a great spot to train and since you're a Bishop you're much more likely to join parties. Monster Park is reasonable, though I believe attackers are preferred, and I'd imagine party quests are good exp as well, like Kenta's party quest.