Nothing can replace physically walking the property.With that being said, this is how I have been able to remotely calculate rehab numbers with the smallest margin of error:First I determine the condition of the property using one or a combination of the methods below: Most obvious: Get pictures  of the current condition of the property  (listing, google street view, zillow, etc), if available.Get information from the seller on the condition of the property- Talk to the seller or get a sellers disclosure if it is listed on the MLS. 

The first thing I would do is see if the physical wires ARE in fact wired independently.

My question is this: How do Remote Investors network or begin providing value in a space they are not physically in all the time?

By changing the locks, they're breaking the system, and thus putting their well being and the properties well being at risk. 

Therefore, there is economic AND physical vacancy for your area that should be factored.

If you were there for 333 of 365 days (indicating you are qualifying under the physical presence test), then you will not get the maximum exclusion.

Do I need to be physically living in my primary residence for 365 days?

Are you looking to invest in tax lien certificates or tax deed auctions for physical properties 

Also, is there any benefit in being a GC when investing OOS, since you physically cannot be the one to perform the rehabs?

You could put in an offer subject to a physical interior inspection, or you could assume the worst about the interiors and the tenants and write the offer that way.