The “crisis” here will be over in 1-2 months, some lingering effects in certain sectors.....but essentially back to normal. 

@Jacob Sampson agreed that normally payroll is much larger. 

While we were due for a recession anyway, this type of dip is too much to be any sort of new normal. 

So even if there is a temporary slowdown, once the overblown mass hysteria dies down things will likely return to normal with a bunch of pent up demand that's been shut in doors the previous few months.After all, it's not like housing demand is suddenly going to go away.

Can I buy a normal single family house that is 3 bedrooms and rent it out to my friends while I live in it and it be "eligible" as a house hack?

I would not normally consider this strategy.

How to adjust to the new normal?

Rates decoupled from the normal co-correlates weeks ago.

During normal times (the virus is not normal times), I would think 5% long term appreciation is not aggressive, but I would choose more conservative of 3% or 3.5% in my projections.  

Assuming you have a 'normal' DTI and aren't the CEO of a Fortune 500: She will need to demonstrate that she alone, without your help, has been making the payments for 12 months, before you can realistically hope to get a mortgage.Assuming pre-covid mortgage guidelines.