I do not see a way to PM with the app so here are a few more details.

There is a podcast featuring @Alexander Felice on this subject.

That's very true that looking at the comps of an area will be a good measure when prospecting the ARV, but I was just curious more specifically with the physical features to fix up in general... the features that tend to hold the most weight in calculating ARV if that makes sense. 

I will be putting a section in the lease about living in a historical house that states the house has historical features such as this banister and landing that has a gap of more than 3 inches between the posts, the current standard, and that a child could put his head through the spacing, and that the banister height is lower than is currently used for fall prevention.Other things that are not historical such as putting in the GFI outlets by the sinks, I just do for the safety factor. 

I like the search features: https://www.biggerpockets.com/search

Have you ever used the Marco Polo app? 

Hi Jeff, you are using the Auction.com app, right?

I like the search features: https://www.biggerpockets.com/searchAlerts can be really helpful too: http://www.biggerpockets.com/alerts

Does anybody know of a website or app to determine rental percentages in certain areas?

Use things that are turnkey and cost effective: $125/mo is my website, email server, loan application, document portal, calendar scheduling app, all the little pretty bells and whistles that consumers expect you to have, and then you gotta read a book a year ($25/yr) on SEO since that is always changing. $60/mo is the loan origination software. $60/mo is the interest rate comparison software that pulls rates from hundreds of lenders.