If you discover you can have the zoning certificate resolved, when he still can't sell months later tell him you'll buy it with all those issues at a much more discounted amount.

Due to no experience, I'm also looking for legal help in drafting and/or negotiating the purchase agreement, reviewing title reports, working with the title company to resolve any clouds on title, preparing the deed/attending the closing, etc...What is a reasonable rate to pay for a real estate attorney to represent me on such transactions?

I would think that has been resolved, but not sure.

I can also see that you guys have negotiated how the profit will be shared but I must also let you know that for any partnership to be successful hugely depends on how concrete the partnership agreement is and must include  your rights as partners,  how you guys will resolve dispute if any arises and of  course how to terminate the partnership in case of any mishap or uncertainties. 

My experience is that in person meetings at the project site can serve both sides to level their heads a little.I would agree that you would not want to release any future money until you've resolved your differences and have a signed lien waiver.I have not had so much luck with the lawyer route.  

Technically no, but ethically I would resolve.  

Will there be a formal partnership agreement with a legal structure and a legal framework that you can all rely on to resolve disputes?

And if they find out you have transferred the title without resolving the note, they could accelerate the loan and call it due in full.

Sometimes it takes 10+ phone calls and weeks to resolve.

OR I just came across a lender today doing 40 year am on DSCR... maybe stretching out the payments even on a higher rate could resolve your issue. ...