What is the deal about how long a state has to ratify an amendment?
Once a state has ratified it, can it reverse its own ratification before the amendment gets totally ratifed into the constitution?
Look here for information on this topic.
Question 1: Unless the amendment has a time limit built into it (most amendments proposed nowadays specify seven years), the amendment can be pending forever. The most recent amendment, regarding pay raises for Congresscritters, collected all but one or two states that it needed, and then sat dormant for over a hundred years until a bunch of states completed the ratification it en masse.
Question 2: This question has not been definitively answered. While the ERA was pending, several state legislatures which had previously ratified it explored the possibility of rescinding their ratification. The amendment ran out of time (it had a seven-year limit written into it) before this question could be litigated.
IIRC, Congress passed a three-year extension to the ERA’s original seven-year limit which was later held to be unconstitutional, although I think it was just a district court that so ruled. The additional three years passed without the requisite ratifications occurring, so the issue was moot… but as far as I remember, the law here is safely described as unsettled.
One constitutional amendment laid around for nearly two centuries before being ratified by the necessary number of states. We now know it as the 27th Amendment.
http://www.access.gpo.gov/congress/senate/constitution/amdt27.html