Couple of suggestions for Polynesia:
For the UU, have it so that it can only go so far on ocean, or only for so many turns. Otherwise, that's not only a huge advantage, it's very ahistorical.
For the UB, if it replaces Temple, you'll have to have one for each religion.
I think for a UP you should have water tiles give +1 or 2

, otherwise those single-tile island cities will be completely unable to produce anything.
For a starting spot, it should be somewhere in western Polynesia. New Zealand is a good place for a capital, though it's a bit ahistorical since New Zealand was only ever an endpoint. From a historical standpoint I'd suggest one of those little islands off the coast of New Guinea, but they probably suck terribly. Spawn date there should be around 0 AD.
I think if Israel is added in the already crowded Middle East just gets more crowded. Besides Judaism and subsequent Christianity being founded there, there isn't that much that separates it from all of the other tiny kingdoms the Independent civs represent.
It would be cool for Prussia/Austria to have something where if you conquer the other one and hold most of Germany, you become 'Germany' (à la EUIII). Perhaps conquering the other one should be a UHV for both.