Depending on your personal finances, shopping for a triplex or quadplex may require the existing market rents to pass a self sufficiency test, to ensure that you will be able to pay the note.

Depending on the loan product used - to purchase a non owner occupied investment property you will need a 15-20% down payment plus closing costs.

I've worked for one of the largest (if not the largest) STR PM in the country and depending on your region they generally charge 20-35% of GROSS revenue.

In the buy and hold situation, depending on what you buy it for, the expenses of owning/taking care of it, and how much you can rent it for, you could have some cash flow each month and have a second property that appreciates each year. 

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Might cause more and more issues once they open it up, depending on where it is.

Depending on the size of your complex you'll likely need the HOA board approval to do this. 

It really just depends on your situation and your budget, and then try to get creative with it.

As a former leasing manager, I would not have charged the reletting fee, and probably returned your deposit, but all that depends on the wording of the lease and property condition.

Depending on where you buy, you might even get new homes with no value add, that you can buy and hold.