I have budgeted all of my properties to use it, and it allows me the ability to own two investment properties 1000+ miles away from where I live.

I'll probably start with 200-300 letters my first time, since I'll be doing it myself and I need to build up my marketing budget over time.

I'm assuming maintenance budget could go as high as 30-40% of gross rents - reasonable?

I'm not certain, but if this is your first out of state deal, I would certainly get 3-4 contractor quotes to firm up that reno budget. 

I would pad more in your budget for repair costs for a home built in 1926.

I also think 500/yr budgeted for repairs is not sufficient.  

I'm already like 2.5x my budget, hoping to get my money back to payoff my debts.Experienced advice is appreciated...

Have more cash.Save more money each month.Look at budget and cut unnecessary spending. 

Is there something else I should budget for?

If they are not analyzing the deal with a budget for vacancy and repairs and operations in addition to your mortgage payment including taxes and insurance, then you should run far and fast in the other direction.Attorney and CPA to make sure you have the right entities and tax structure for your investments.