For the kitchen and bathrooms, would I need to do EVP for potential water issues? 

The structure and roof is good with some issues I want fixed:-covert fuse box to 200amp cb panel-storage shed/garage water damageI’m seeking advice on how to make an offer with either the seller repairing these items (another investor I’m not sure I trust to do it properly) or asking for funds at closing (escrow). 

I’m aware of what material participation is, i just wanted to see if anyone has personally done this and if there were any issues or pitfalls with doing it.buy a million dollar cabin, cost segregation, 200- 250k tax deduction against w-2 income and rinse and repeat?

They were also able to provide new estimates on the work needing to be done including correcting everything the original contractor had done.My question is, should I pursue some sort of legal action or just never get into contact with said contractor again?

In most cases these are not issues that can be easily resolved and typically the damage can merely be mitigated.

I can pre-authorize an amount and if the expense is below that, the vendor can do the repairs without talking to me live4) Urgent maintenance issues - say a pipe breaks, or tenant is locked out.

As others have mentioned (besides the essentials like rates, mortgage, and maintenance), it's important to consider utilities, insurance, property management fees, taxes, furnishing, marketing, and legal requirements.

- Investing with a Friend: Tips on structuring partnership and legal/financial considerations?

There's also potentially some liability protections you can have in place by having the work done by the GC rather than you as individuals (discussion for your legal team). 

Also the course decribing the lot doesn't close by 35'...three parcels adjacent to ours that we share a boundary with have completed record surveys over the last 40 years and have identified and attempted to reconcile the issues using good survey theories (the art behind the math, who gets what and by how much and why).