Is there an app to speak into when doing rental rehab walkthroughs? I would like for this to also link to google docs if possible. 

We use a screening service through our software that provides a criminal, rental/evictions and financial/collections background check.

I am considering developing software to sell to investors to collect foreclosure info from the legal notices advertised by your local attorneys to make researching foreclosures easier.

Do you recommend any property management software?

If you do it yourself, your property management software should help you publish your listing to zillow, cl, trulia (and the rest) with just a click, and when you get the applications be sure to be especially careful screening tenants, especially if you haven't met them.  

The main methods would be comparable sales method, income capitalization method and DCF.I would focus more on the comparable sales method and income approach to figure out if you have a deal or not as most commercial building analysis is done using software such as Argus.So you can look up a few comparable sales to see what they sold for.

As an update to my use of Buildium -- I have moved all owner accounting to a separate accounting software (Gnucash) and operate Buildium as intended, from a PM perspective. 

It takes about 20 minutes per site to post them with details and pictures, or if you are using a good property management software product, it can be as easy as just having your existing property marketing details automatically syndicated to all those sites for the best exposure with least effort.Good luck with your new rental!

I assist a SaaS (Software as a Service) startup with marketing and customer care.

Software is the big mover in the industry.