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. 

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.

Direct booking site to build your own brand and reduce OTA dependence Social media/marketing automation like Social Pilot, Jasper and Canva.Google Analytics GA4 tags on your website to harness your website traffic and build a growth plan based on client data.Adobe Firefly for text to picture, streamlining content creation. 

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. 

High crime + low income = Poor tenants to choose from.  

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.

I was under the impression that the depreciation percentage depends on the year you are doing the filing.