Partnership ended, generating a loss in box 9a of the K-1. Should I report this loss again in the questionnaire for the disposal details (also part of the K-1 interview)?

No, the loss reported on Schedule K-1 is not your loss on the dissolution of the partnership. This is flow-through loss to the partners from partnership activity. 

If the partnership dissolved, you probably have zero sales proceeds to report for the disposal. This may result in either a gain or loss on your investment, depending on your ending adjusted basis.

Additional info:

• IRS Form 1065 Schedule K-1 Basis Rules
• IRS Worksheet for Adjusting the Basis of a Partner's Interest in the Partnership