Not one tax but a stack: federal long-term capital gains tax at 0%, 15% or 20%; depreciation recapture at a federal rate of up to 25%; the 3.8% net investment income tax once your income crosses its threshold; and California income tax, which treats the gain as ordinary income at up to 12.3%, plus a 1% surcharge on taxable income over $1,000,000.

No. Your gain is the amount you realize minus your adjusted basis, and your adjusted basis is reduced by the depreciation you took. The bank getting its money back is not a tax deduction.

No. It is a prepayment against the tax you will owe, reconciled when you file, and refunded if too much was withheld. It still comes out of your proceeds at the closing table, so it affects your cash timing.

California treats the gain deferred in an exchange of California property for out-of-state property as California-source income, and requires FTB Form 3840 to be filed every year, regardless of residence, generally until that gain is recognized. How that applies to your own sale is a question to work through with your CPA.