Once you have a property you will most likely hire a property management company for a month % although I know people who have a smaller portfolio that have local leasing agents and handymen connections to do the important parts of owning property and they just purchase a PM software to save money.

A lot of contractors do not utilize an estimating software to make it easier to provide a line item estimate.

It's my butt in a chair in front of my computer, leaning into my monitor with my spreading gut pressed up against my desk, going through public records to find the prices that similar places nearby actually sold for, looking at pictures of these places wherever I can find them, utilizing my understanding of the neighborhoods I know in my target area.The right place for me to start from was to shoot for is a range.

Does anyone know a software/website that offers a paid version of a nationwide screener?

This is just my opinion, maybe others have great luck with software.

Now, if you are looking for duplexes, triplexes, and fourplexes, then the whole MF mailer strategy should work and any one of the software you mentioned is fine.

All of the accounting software seems like pretty serious overkill for a single-member LLC that flips houses and is taxed on a Schedule C form. 

I just finished Rental Property Investing by Brandon Turner.  The book mentions training programs for use of QuickBooks but neither of these websites exist anymore.  I'm more of a pen-to-paper person (because I'm 50+ ...

If so, then what software programs would you suggest to get a solid number of high quality leads/list?

I have been doing a lot of research recently into different management software.