If the rent isnt paid on time you are going to file for an eviction , then tell them "once an eviction is on your record NO LANDLORD will rent to them .

Whichever loan was recorded 1st, is the first mortgage.

The main reason properties go to tax sale is people didn't get the bill because the address of record is wrong. 

Their names are not currently on the records at all.As of now, I have no intentions of giving them the rent I “owe”, or leaving within the 30 days, as I don’t currently have the funds to do so.

Transfer and recordation taxes.Better make sure the condos are warrantable before you buy, or you might not be able to do the refi.

Is that better done via email for a record of the conversation, or is a letter better?

The 23 single unit owners are all mostly investors (Tax Records) and only 2-3 of them are homesteaded, per FL law I would have to give them their full buy price (which is far below market, but I would still be giving them market price ofcourse). 

Checking the title records seems like a good idea.3.

The best way to get private money is consistently do successful deals and build a track record of success. 

For newspaper select The Record Reporter.