I may call them to see if they can give me some data.

This is basically how realtors and even Appraisers run comps, yes they may use the "MLS" but that is where Zillow and Truia get their data as well.

I don't mind the pressure of a 1031 - because I'm thinking I can just find 3-4 "average" (not amazing) deal properties with cash flow, and even that would be significantly better than the not-much-cash-flow state it is in now.But the question is still - does it seem like a property that I should hold onto for the appreciation based on the data? 

I would take that data with a grain of salt though.

I use PropStream for all my data needs. 

Also, are the expenses from the agent marketing data?

Building your network is invaluable and you'll find that there aren't many young people actually doing anything in RE so often times experienced investors will be enthusiastic about helping someone your age. 

To do % of two numbers, I always cheat and go to this calculator: https://www.marshu.com/articles/calculate-percent-with-simple-number-percentage-calculator.phpEstimate: when pulling a list from a data source (like listsource.com) - the site estimates the equity by how long the mortgage has been in place and estimates payoff based on a standard amortization rate. 

if so,How accurate is the data and is it real time?

Unless you give them the company tax return - in which case, they see all the same data as they would on page 1 of Schedule E.