US property sale

My clients are domiciled and resident in the UK. A few years ago they purchased a property in Florida which they also rented out. The property has now been sold.

The sale was agreed in November 2012 but the actual paperwork was not completed until February 2013. Because the US tax return is prepared on a calendar-year basis could readers please advise in which year the transaction should be reported in the US returns?

Based on UK legislation the sale of the property did not result in a gain. Although we understand that there is no capital gains tax in Florida can readers advise how the computation should be computed?

Because depreciation has been claimed as an expense in the US tax return is there any interaction between the income tax and capital gains tax computations? There is about 10% US withholding tax and...