Hey Local BP'ers,Must warn you, this is a lengthy read but an interesting scenario that could happen to you. 

I purchased a non performing note on a vacant property a couple months back and would like to start the rehab during the lengthy foreclosure process - I am under the impression that since I technically do not have possession of the property I am only able to work on the property through a receiver.

I did write a pretty lengthy post on this topic that you can read HERE. 

I have a pretty lengthy post somewhere here on the BP forums going over how the VA loan works with using it again.

I liked my attorney, but the purchase contract he provided was VERY lengthy, and at the end of it all I had no deal and a bunch of legal fees. 

You would request a variance to the zoning code there is usually a lengthy and public process to do that, notification of abutters, etc. and "I want it as an investment" will not be a compelling reason for a zoning board to grant it.

There could be taxes, liens, a first mortgage on the property… the property could also be occupied (or burned down) and if occupied you would have to go through a lengthy eviction process.

On another note, you do realize any house left unattended for lengthy periods will expose you to a multitude of problems, for example:Mold, rodents, insect infestation is almost certainCarpetbaggers, homeless, and or drug addicts may become a problem that could ultimately be your responsibilityWhat is the city ordinance?

This a very specific legal question that will have a lengthy answer and likely you will have follow up questions.

There is a reason why you don't see in-depth posts about lengthy turnkey experience.