My question is, must I have some type of rental agreements assignment from the seller?

Is it legal for the man to be removed from the lease agreement? 

If your contractor and the current tenant showed you enough to make the deal a "no go" for you, then you should be able to terminate the purchase agreement (and only lose the DD money...in NC).I like the idea of getting quotes on making the repairs, and presenting (still, within the DD period) the seller with the problems, quotes, and a request to reduce the price by $xyz....or, you could just decide you don't want to deal with the property since it has xyz issues.  

Something in the partnership agreement?

Some of this depends on state laws, your level of skill, and the judicial system.Yes, you should have a penalty in your lease agreement.

Our rental agreements are now month-to-month, which has given tenants the flexibility to move in the event of a job loss or illness during the pandemic, and by the same token, the owner can issue a 30-day notice of non-renewal to get rid of problem tenants without having to go through a lengthy eviction process.

Fine print / requirement to use settlement servicesMake sure you read the listing agreement and there is no requirement to use the listing agents preferred escrow, etc.f. 

If a seller understood the situation more, they would push back and renegotiate the listing agreement for an unrepresented buyer.

We were not expecting having to share our loss of rent reimbursement but it was written in our agreement.

Should I have the tenants drop another security deposit for the new 1 year lease agreements even though some of them have been there for 2+ years?