You might want to do a little research on what are called pay for delete arrangements depending on how old your collection accounts are.

He says he doesn't have to pay us capital expenses because we didn't actually pay that, the previous owner did.

I didn't implement it because I didn't feel comfortable setting up an official government-looking website and letterhead, tell them you will send them money to pay their taxes, then tell them that you can't.  

well, you do of course and yes, even if your DSCR lender does not pay to report to the credit bureaus. the credit report is not, nor has it ever been the arbiter if you have a debt or not nor is it the only way the an underwriter will see that you have a debt.)

This is free to you as the Landlord generally pays commissions to this broker.

I'm a boston-based investor,  looking to buy a multi-family unit and plan to use my residence unit as a STR. 

I'd also find a real estate agent who knows the house hacking strategy or has house hacked themselves if you plan on using an agent. 

If you must pay, offer to do free work for a rehabber, tax lien buyer, or just dpent time in tax office, I have and it works!

There will also be many unknowns that you can plan for or build a cushion if an assumption is wrong.

I think I have to pay $$$ if a lawyer generates the forms so I don't want to do that.