1. Slave get stuck? No, then you moved the slave which stopped follow, or you have very bad lag or you went through a phased area.

2. Move your main so the follow slave turns to face the correct way or use click to move/interact with target or get a focusing lens.

[item=41367]Dark Jade Focusing Lens[/item]

3. No idea. I used to like priest holy nova, went well with mage, but that last expansion and not PVP. Disc priest - penance?