Because I sent them an e-mail and they sent me the link in the original post (https://www.cmha.net/housing/landlords/rent.php) that shows that amount.

Without an operating document, it's unlikely they could sue you unless it's in the city rules that all homes are responsible.

Send a copy of the receipt on an email the old tenant itemizing all deductions.

When selling for sale by owner (FSBO), ensure all legal documentation is in order and consider consulting with a real estate professional or attorney to handle the lease transfer and legal aspects effectively.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

I've shared with my clients and the investors in my network and happy to shoot over via email if helpful!  

Hopefully, you've approved a bid they submitted, so the cost is fixed - unless they can document the need for acceptable change orders.If they are charging hourly, then, yes, they may be able to charge you more the longer it takes.Keep in mind, your PMC is unlikely to have an exterminator and other licensed contractors on staff.

I get emails of the properties from wholesalers with photos.

The registered agent is listed on all the documents, not the property owner.Your Operating Agreement should list members and authority. 

Is there any document within the BP website?