Also:_________________________________________________________________________Recommend exploring as many sources as possible to get referrals AND cross-reference them to get as much accurate information as possible.Check out NARPM.com, BP’s Property Manager Finder (BiggerPockets: The Real Estate Investing Social Network), etc.Also, encourage you to learn from the mistakes of others - by reading posts here on BiggerPockets about owners not having their expectations met by their current Property Management Company.

And if not, what other suggestions would you have for getting the comps I need to accurately assess ARV on flips? 

Was your post accurate or a mistake?

Those assumptions above may not even be entirely accurate, that's just what I've been told plus what I've deciphered from the zoning table. 

How accurate are websites like Airdna?

My wife and I have never really followed the $$/sqft. approach because it's not as accurate.

Can anyone verify if this is accurate?

A PMC is the ONLY one that will deal daily with your property.Here's some copy & paste advice on hwo to screen PMCs:Recommend exploring as many sources as possible to get referrals AND cross-reference them to get as much accurate information as possible.Check out NARPM.com, BP’s Property Manager Finder (BiggerPockets: The Real Estate Investing Social Network), etc.Also, encourage you to learn from the mistakes of others - by reading posts here on BiggerPockets about owners not having their expectations met by their current Property Management Company.

I was wondering if anyone had any recommendations on how to calculate a relatively accurate 5 year rent growth for a market?

They are really the only ones that can give you an accurate answer to your specific situation.