Hi Lolabola
In terms of your questions about ISA, this is not a tax free vehicle in the US, therefore the interest, dividend generated on this account will be taxable in the US. THis does not come under the $80,000 exclusion as it is investment income (and not earned income).
In terms of selling your house, if you are married to a UK citizen, when you sell the house you may have to report half of it on your US return. However if the house is your principal residence and your portion of the gain is $250,000 or less nothing is to be reported on your US return. The rules sorrounding sale of houses are complex, therefore I would need more information to answer your question properly. Therefore you can call me on 0208 466 9297 if you like to discuss this further.
Helen