Better to invest in your backyard so you can learn and use your commissions for price reductions. 

May see some slight reductions but we are most likely not going from say 7% to 5.5% unless of a major economic crisis which would also cause home prices to get hit.

I see price reductions daily.

This doesn't account for transaction costs and reduction in leverage as you pay down the mortgage which accounts for closer to 2-3% less, so you 12-18%. 

Simultaneous to that, negotiate price reductions to the greatest extent possible because of this extra cost you are incurring. 

At one point Elon and Vivek talked about a 75% reduction in staffing of the federal government. 

Unless the seller has to be immediately out of the mortgage I see sub-to as an excellent cost reduction strategy. just reading between the lines.. but if the bank says they will take 91k for it sounds like the mortgage is in default so a sub to might not be possible.

You likely are not going to get a reduction in your taxes.

They may also require US credit history, although there are a handful that will not require a US credit report for an increased rate/ reduction in LTV. 

Do they have insurance and property tax reduction reports in their study?