And they make sure that the seller follow their disclosure requirements or ensure that buyers complete their due diligence and generally facilitate the transaction.

@Andrew Faukner  Disclosure: I no longer practice tax accounting, so this is just my opinion. 

There was nothing on the seller disclosure form (form 17 for WA) to put a note about a tree.

It would be a criminal act to do a lease option or even a leaseback on a short sale if that was not disclosed and, there would NEVER be an approval for a short sale with that disclosure so, if it did happen, the borrower lied.

I contacted our realtor for the disclosure agreement which we never got and she said she's not sure if the sellers were required to give us one since they were renting out the property to tenants.

I believe you are able to do the repairs yourself, if you're hiring someone, they might have to be certified (or that's only when you KNOW that there's lead paint, ie having it tested or it show up in the disclosure)

Could have issues with clawback or non disclosure

Hand over those disclosures detailing all flaws with your comps. 

Do not let a realtor try to convince you that it will be difficult as it is relatively simple, especially if you are buying or selling off market for cash.I downloaded all of the required contracts and disclosures for the state of Nebraska from an online source.

You will have to set up an account and sign a non-disclosure to get access to these, but that's pretty easy to do.