Personally I farmed Orchard for slayer XP and explorer completions. Doing just the explorer you can usually get about half the rares and 1-200 slayer. Between my toons I have traditionally had so many mats that I have helped equip several noobs with Minos without them having to set foot in Orchard, and I know I'm far from the only one. You make great points about Relic, the only problem being that relic is one the the BEST quests for XP at it's level, so optimally you want to run it for streak at 14 and not have ruined that with 3 casual runs at 9th. Ochard is farmable at 10.
As for turns... again it's a matter of play style. The OP didn't request a healer build, so I'm working on the assumption that he wants self heals and anything above that is gravy. If he wants to be a capable healer for a party then he should certainly consider that for his charisma, otherwise 10+tomes+items should be adequate for a toon that can dish out solid damage (and has heal spells and unyielding sovereignty).