If not LVP that does not have a rigid backer will conform to all the underlying defects in a few months. 

Real estate licensing forces those in the profession to conform to a set of ethical standards and gives the consumer the legal recourse if they do not.

*Conforming down payments

I don't know about your personal situation but when I bought my primary residence there was a rate cut if you were "Super Conforming" so I put enough down to get that slightly lower interest rate. 

Two things they will remark on - whether or not the units are legal and whether or not they conform with zoning classifications.

Once your approved you can begin your search for a home of your own, typically as a first time home buyer you will find that there are programs that let you put as little as 3-5% percent down in order to buy a home that satisfies the lender’s guidelines according to its value and conformity.

Sometimes non-conforming uses/setbacks  can stay if repaired but cannot be rebuilt if they are removed. 

If you are going owner occupied, secondary market conforming/FHA/VA it might be a tough go.

Additionally, even if you do get the variance successfully, you will likely need to conform to current construction codes for 4 units which includes sprinkler system, fire panel, and other fire code items.

In my area, it would be against the law for me to shut them off, and the only recourse would be to serve them a notice regarding not fulfilling lease requirements (non payment of utilities) and then evict unless they conform.