If evaluating something like this be aware that even though it may be grandfathered in...the fire marshal can deem that the homes are too close based on safety concerns and rule that you can’t bring in new homes 

(I've already begun work on spreadsheets, but finding out the specific fees and management rules for each condo/condotel is daunting and I don't want to start actually shopping until I know a lot more about each condo association).- I am totally aware of the problems with condos.

Each state has its own rules about what can and should be done with items left by a tenant.

It is harder today to differentiate between companies and offerings than ever before, but that doesn't mean that running numbers on Turnkey properties is any different than other single-family homes.The 50% rule is a well-accepted, quick assumption calculation for determining net rental income on a single-family house.  

I know some of the keys have rules against anything less than a month though.

The property does not have to be occupied, but the lease does need to be executed.  25% equity is usually the sticking point for most with an FHA loanConventional loans will only require the executed lease to count the rental income of the property you are leaving.It might not even matter if you could afford both loans but if you need rental income the above is what you need to know.OVERLAYS - having said all of that, the bank could actually have rules that are different than what I described above. 

Also not sure if your condo has many requirements for tenant approval and abiding by rules for any short term rental so do you find it be relatively simple to handle from another state?

The one in the redfin link, show that:sold date:   3/30/2018sold price:  $290,000Total Rent (inside the listing details):  $3,250  ($900 + $850 + $750 + $750)For long term buy and hold, it meet the 1% rule requirement. 

Any advise on the rules/ requirements for Missouri would be helpful. 

My question is,  are there rules, regulations, qualifications or RESTRICTIONS on using a line of credit on a commercial property to purchase other properties?