He set up my account and sent me on my way!

They can provide a more accurate assessment and potential repair costs.When dealing with homes from the early 1900s, it's prudent to overestimate your renovation budget to account for unexpected issues.

Electric, gas - Where I am at you can link multiple properties to one account this helps if you aren't doing that.

I don't consider it rented until the deposit is in my account.

The first is the age of the home issue and pretty much expected and I think would have been accounted for in offer. 

I contend the more people push for direct bookings the harder for AirDNA to account for it and as said above they have no way to account for uniqueness (location, amenities, build).

I was going to draft up one contract with each LLC as a separate "Owner" with the authorized representative for all, the actual owner, to sign the one contract for all legal entities, but they didn't like this and want to keep all documents separate.I gave them a VERY competitive price quote based on the total portfolio as 1 account with the total number of units.

For a portfolio of that size, I'd want 10-15k in a savings account specifically for my rental portfolio, IE separate from your personal emergancy account.

(Source: Journal of Accountancy, IRS Publication 925, Section 469 of the Internal Revenue Code)

You would use Form 3115 (Application for Change in Accounting Method) to change your depreciation method.