You enter the K-1 *exactly* as you have in the past. There's really nothing special about it. However, that final K-1 you received "MUST" have that "final" box checked on it. Then when you enter it in the program, remember to select that "final K-1" box in the program too.
The system will know that this is a final return when you indicate "the partnership has ended".
Yes there will be additional questions that need to be addressed as you (TT) will need to determine the overall gain or loss on the disposition of this investment.
You should have been tracking your basis in this investment.
So the system will ask for the sales price - this is your liquidating distribution received (not normal distributions, your liquidating distribution).
The system will ask for your basis - as noted above, you should have been maintaining this all along. Make sure your basis is not adjusted for any liquidating distribution.
Doubtful the system ask for principal payments unless you indicate you are receiving payments over a period of time.