I am confident I can capitalize the renovation/construction/zoning costs, but what about property taxes paid in 2018 (all of which exceeded the $10,000 SALT cap based on our W-2 state taxes, so none have been deducted). 

I am very confident on 800/month as worst case and top end being 900 to 950.   

If you are confident you can bump up rents with those improvements its worth a shot. 

My friend was able to provide me with the 2 estimates that he received for the foundation work, so I'm confident in the scope of work there, but I see your point about the friendship.

It could depend how confident you are in the ARV. 

I also realise speed is a necessity when using loans, and I am not confident enough in my abilities to accept OPM at the moment because i might lose their money on top of my own.

To find land, easiest way is a simple google research such as “land for sale El Paso texas” and im confident you will land in pages from sellers of land.

Ideally 6 months but only thing that can hold us back is the selling of it more than the actual rehab because my cousin and I are confident we can get this done is under 4 months worst case scenario 5-6 months if we run into unexpected "surprises".

With my market and putting that amount down payment, i'd be confident to say i'd cash flow around$ 500 to $1000 between them once rented.I DONT want to sell the CA home straight up, i'd be taxed to hell and plus doing a 1031 exchange allows me positive 180000 reinvest and that goes far in Idaho.

My main one is that my confidence is there as I know a lot of military rent there and I'm most knowledgeable of the going rents/sales in that location.