So, I have an opportunity to buy a house for roughly 20% below current market value (of course I'm sure this will change now with the coronavirus and ensuing economic instability).

I agree with a lot of your assessment on the market...this is different than a normal economic downturn due to the fact that businesses in otherwise good condition are longer receiving revenue.

We will get through this but no one knows how long or how deep the economic impact and effects on housing in the short term. 

Already announcing mortgage grace periods for economic hardship.We are nearing the point of maximum anxiety, in a few weeks taht will be gone and we will work the problem instead of freaking out.

I'm certainly not an expert on mortgage rates, but I know they're determined by supply and demand in the bond market.

Your continuous learning and searching with the help of experts in the industry over the next 4-6 months, you’ll be ready to purchase your first (or next) property in NO TIME!

So, converting to a duplex may also be an option.Ultimately, I can’t give you specific advice on your situation (or refer you to someone who’s more of an expert on zoning issues, if appropriate) without doing a full investigation of the zoning ordinances and zoning maps. 

Up your economic vacancy significantly, and let’s hope it doesn’t last beyond a few months.

I would request owner unseal hatch and have a foundation expert go take a look.

With your continuous learning and searching and with the help of other experts in the industry, over the next 4-6 months you’ll get more extra $ earning in NO TIME at your convenience!