I'm in a similar campaign, and my cleric/contemplative has been as close to a pure caster as a cleric can get. (She went from 5th to 13th level without ever drawing her sword.) I would recommend Pelor for the anti-undead goodness. Pick the Sun domain and the Glory domain (from Complete Divine)
You do stop improving your turning ability, but you can bump that first by picking the Glory domain (you want that early, but if not, you can still pick it up later as your bonus Contemplative domain). Later you can bump it further with a Phylactery of Undead Turning, and 5 ranks in Knowledge(religion) will get you a bonus to turn attempts. All of those together should have you turning as a cleric 4 levels higher with another +4 to the turning check and a bonus 1d6 in turning damage. Finally, the Quicken Turning feat (turn as a free action, and still get a spell off in the same round).
Another feat I would suggest is the divine feat "Domain Spontaneity" from Complete Divine, to let you burn a turning attempt to spontaneously convert a spell into a domain spell, just like how you can spontaneously convert into cures. So in the fights against non-undead, you have a lot of flexibility in your spellcasting.
If you haven't had much experience playing a cleric, be sure to get a wand of Cure Light Wounds, and replace it when it gets low on charges. Get the group to help pay for it, so that you can use your spells in combat and still be able to heal them after the fight is over.
If you're doing point-buy: Strength is only useful for the first two or three levels. By then your spellcasting should keep you busy throughout combat and you will already be outstripped by the fighter types. I would keep it at 10. Ditto for Dex. It will be useful at first, but once you get your heavy armor, it's a waste. Wisdom is most important, then Charisma or Con, depending on just how heavy the undead element will be. Int is nice, but your only really needed skills will be Knowledge(religion) and Spellcraft. Even Heal is not really useful past the first level or two.
Finally, I recommend a Strand of Prayer Beads as soon as you can afford it. The once-per-day bump in caster level is worth the price of the entire thing, and since you will probably not be spending any of your gold on weapons, you should be able to afford it before too long.