Don't cut off your nose to spite your face.

The price is the price, and unless they've made some kind of egregious error, your questioning them is not going to change anything. Remember that even though all the nitty-gritty details (about taxes, escrow accounts, etc.) are new to you, the people who prepared the paperwork do all this a couple of dozen times a day, and almost certainly know what they are doing.

If they've added some closing costs to the mortgage instead of making you pay out-of-pocket, that's good. At these low interest rates, I'd prefer to borrow as much as possible (within reason).

The risk you face in delaying the closing is that rates will jump and you will get stuck with a higher rate. Frankly, that's a risk I would not take. Certainly not over questions about a piddly amount of money like this, in an area where the answer to the question is not likely to change anything.

It's annoying when things like timing of taxes is such that you get caught in a cash-flow pinch. Been there myself. But all it does is shift the timing of the payments -- it's not that you will have to pay double tax or lose your house because the tax didn't get paid.