This is a boiled down version of some responses I gave to my gaming muchachos Paul & Dan'sWandering DMs discussion of Clerics from a couple weeks ago.
1: I tried to think about magical healing from whatever pulp literature/cinema I've encountered, and the only example I can think of is the scene in the 1st. Conan movie where the wizard played by Mako healed Conan up in some kind of special effects laden ritual after the disastrous raid on James Earl Jones' snake temple. (Although I think that was also more about curing some pretty heavy poisoning problems. Snake cults... whattayagonnado?) So that's a data point towards maybe just handing a couple healing spells to wizards and being done with it.
I think one of the over-arching issues with finding historical or fictional precedents to the concept of healing magic is that D&D's conceit of health as a numerated commodity just doesn't jibe with reality or fiction. Hit Points are an extreme abstraction of a very complex state/process, a very game based vital resource with healing spells and potions being a very game based solution for replenishing that resource.
In other words the fictions that we base the game on don't turn up with a lot of healing magic because the authors weren't thinking in terms of the characters having some kind of abstract number tied to their health that needs topping up. Generally, a character is either fine until they receive a dramatic enough wound, or any reference to damage they've taken is just there to magnify their courage and determination or heighten dramatic tension.
Often, I think, the literary trope for wounds and healing is the hero gets so roughed up they can't continue, and wind up holing up in some out of the way hideout and getting nursed back to health under the care of a sidekick or sympathetic, otherwise powerless ally, and then coming back healed up and determined to clean house. A prime example of that trope is Yojimbo/Fistful of Dollars/Last Man Standing, or when Darkwolf heals up Larn in Fire & Ice, or Lupin III's dramatic (and perhaps ridiculous) injury and comeback in Castle of Cagliostro. A lot of other examples abound.
The problem being that what works for a single protagonist doesn't really do the same for a large group of protagonists, and spending days or weeks out of commission under the care of a kindly old man or sympathetic schoolmarm isn't really what the game is about.
The fact that a player has a number on the sheet that kind of gives them a meter for how healthy their character is at once a help and a hindrance. A lot has been said about how abstract the system really is, and I think HP is a big part of it, but I also think it leads to questions that don't get asked in the fictive examples above. The biggest one being "How can I make this number go back up?"
Having the HP number there in black and white means that it's harder for the player to accept the literary hand waving and drama building that allows characters in books or movies to play on at full force through terrible punishment. Long story short, I think this is a prime example of game mechanics grinding gears with narrative.
2: I heartily agree with the whole world building aspect that clerics engender, and actually I find it slightly problematic from the viewpoint of a practicing Christian. Since, as you point out, most of the cleric spells are cribbed from the Bible, the general commodification of the miracles performed, combined with having to make up other sources of those miracles to stand in for the big guy upstairs, is a little hard to reconcile. It would still be a problem just declaring capital G God as the functional religion in a D&D game, 'cos the Lord isn't a vending machine in the way that D&D clerics require their deities to be, and so that doesn't work for me either. (I mean, I'm all right enough with coming up with pantheons and such, since you can approach it as an exercise in creative mythology, but still, it's a little sticky.)
The miracles described in the Bible are all meant as teaching metaphors as well as demonstrations of the Almighty's power, in fact there's one passage in the Old Testament where Moses gets in trouble with God for performing a miracle wrong. He strikes a rock to produce water in the desert, rather then simply waving his staff over it, essentially messing up the Lord's demonstration of how faith works. Miracles are always granted with a greater purpose, and the personal convenience of a bunch of jumped up looters is kinda pushing it.
Long story short, I'm kinda in agreement that just letting the matter of pantheons and patron deities not be so front and center is the way to go, if you're still gonna include clerics. I'm okay suspending my belief for a game of make believe, as long as theology, or pseudo-theology, isn't the main thing.
3: I'm kinda unsure about Turning Undead being that big a problem. You guys both talk about it nerfing an entire class of foes, but on the other hand those foes are particularly dire, with the higher level types' immunity to conventional weapons and paralysis and level drain if you're playing them by the book. Sure you can't just turn orcs to dust, but you can stab 'em, which doesn't work for higher level undead unless you got magic items.You can also Sleep, Charm, and Hold Person 'em, which you can't do for any type of undead.
I think here's a point where a happy medium could be reached where on one side turning isn't an automatic kill switch and on the other the undead are more survivable. (I know Paul has a couple of lists of alternative undead powers that he uses instead of bog standard level drain.) Having tactical ways to drive the unquiet dead back or escape their notice is deeply ingrained in folklore and literature. The idea of a Van Helsing like figure (NOT the Hugh Jackman version, tho. Oy...) in the group is still kinda appealing.
I actually very much like that interpretation of clerics, and it informed my cleric character Deacon Silver in Paul's B/X campaign. I think one of the advantages I had in taking that approach was that I was the most knowledgeable about the lore of the game itself among that particular group of players, so it was a natural thing for the rest of the party to turn to me and ask "So what are we dealing with here, Deacon?" It was one of my favorite parts of playing in that campaign in that role.
That being said, you could still have the aspect of exorcism/turning and cut player character clerics out of your game. Relegate the experts to sage status, and allow them to pass knowledge for combating evil monsters on to the party. (In "Dracula" for example, I believe it was Lucy Westenra's suitors who were the ones who drove the stake into the "Bloofer Lady" while Van Helsing merely stood by and advised.)
Maybe, like finding traps, turning undead is a thing any party member can do, as long as they're properly prepared and equipped. Make it a power attached to certain relics, for example, and have those relics operate at a certain level of clerical powers. i.e.: St. Hieronymus' knuckle bone in its silver case can turn undead using the 5th. level column on the table, vs. a small folk charm given to you by a babushka in the village that only turns on the 1st. level column. It's essentially taking the ubiquitous healing potion solution and applying it to turning. There's a piece of equipment for that.
I went into this a bit a while ago here on the Sandbox, when Jeff Rients was talking about monsters that required plussed weapons to hit.
4: In a related point, Paul mentions "Speak With Dead". This to me seems like an ideal spell to swap over to the Magic User's list. That, essentially, is where the term "Necromancer" came from, after all.