2. Do you believe that the bitcoin price would at a minimum, increase 5% or greater per year on average, handily beating your current mortgage interest rate?
If again the answer is yes, then
HODL your bitcoin as an investment and keep paying your mortgage payment. Payoff your remaining mortgage years down the road with your bitcoin, and live on the rest.
This right here. Compare the cost of keeping the mortgage to the expected return of the bitcoins. I strongly suggest hodling is going to be a far better result.