You'll need your own credit card processor for that one too - Square and Stripe are integrated with the platform.

But the best ways to get started are, in my opinion: 1) save up enough for a 10-20% down payment and then save a lot more on top of that for reserves, overages, and any unforeseen repairs.    2) have your financial house in order and have credit above 700 to get more favorable rate and terms from lenders.   3) speak to a loan officer that is experienced with fix and flips and get the necessary documents together for a pre approval (typically not much required, usually a valid ID, LLC docs if any, and two months of bank statements showing funds for down payment and reserves). 

.- Investment Lock-Up: While there’s a chance your funds could be tied up for a bit, if the property is well-designed and in a desirable area, you might see appreciation that allows for refinancing sooner than you think.Buying an existing property:- Less Risk: Existing properties come with a track record, so you can analyze their performance and potential more easily.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

These will still require a decent credit score and at least 25% down payment.  

You can track individual funds using your spreadsheet or software.An LLC is useful for two things: anonymity and legal protection.

Whom am I to believe, you, a professional in the business for 10+ years with a verifiable track record of success and a willingness to provide information based on your experience and education at no charge, or my guru who has never run a note business and has been banned from the securities industry for life for violations related to stock dumping 6 years ago?  

It is not taxes, does not report to credit, does not affect your debt to income!

You only need a place to track tenant information, payment history, maintenance, etc.

My Lowest possible property purchase price would be $68,750, with 20% down payment and we can allow up to a 2% seller credit attached.We can connect if you would like to learn more.