If you look at it in a vacuum and remove any emotion or risk tolerance, it should simplify the question to look at each avenue for it's financial efficacy. 

You can have a contract between you and your sister for how the deal pans out, who does what and who makes how much, but one of you could be solely responsible for the debt, which might simplify the process. 

We simplify the crazy and get them the best offer possible.

This is simplified criteria, of course, but you get the idea. 

That’s a very simplified version of the plan and why I’m not concerned about price as much.

If the software is not simplifying your life or making you more accurate, you shouldn't use it.Software does have extremely helpful features like online payments, marketing syndication (click a button and your property is advertised on multiple sites), electronic document review/signing, maintenance tracking, and owner reports.

I have a very general and probably overly simplified question.

Kinda on the fence of digging into be a long term rental property or just selling to simplify. 

If your company's revenue per year is less than $ 2,250,000 (two million dollars ) or 150 000 000 RUB, You can use the simplified taxation system with only 6% tax. 

Once you get use to the platform it easy to manage, create templates, do background checks, built-in digital signature, application process, notifications for you and the tenant when past due or contract end dates, online payments work great for my tenants and having a maintenance portal to manage issues simplifies communication when tech will show up and it has a decent reports and tax generator (i said decent not great).