There is no 1098-INT.
I think you may mean 1099-INT. This is used when you PAY interest, so that the recipient has to report the interest income.
1098 is used when you RECEIVE mortgage interest, so that the payor can deduct it, and so IRS can make sure that you report it as income.
RE: 1099-C. You don't need to file it. The mortgage was not foreclosed or abandoned, so it's technically a "work-out." You don't report cancelled debt, and it's up to the buyer to reduce their basis in the house by the reduction in principal. (Give or take. it's more complicated than this, but this is the basics.)