It's a win-win for everyone. 

Personally, I wouldn't even start looking for deals until this was lined up because when you are up against a lot of excellent cash buyers and you are interested in getting deals with equity, you need to have the ability to move quickly and decisively---be the buyer that is remembered and the deals will come :) 

A client of ours in the past told us that he was sued by a tenant for having that tenant pay for his share of the roof and the tenant ended up winning.

Again, I'm brand new and curious if there's a potential deal here for a win-win.

If you win the auction, personally, I'd hire an eviction attorney for an unlawful detainer action and be done with it.

The comps in the area avg abt 1700 for monthly renters, does anyone have any advice on how I can structure this partnership to be a win win?

Would I have an opportunity if I win the bid (due diligence period?)

The key is to get them on the phone and find out all the info you can, build report and create a win win.

When you win the bid at an auction, do you then have to purchase the Tax Lien Certificate separately or is the amount for the Certificate already included in the bid?

If the guy doesn't have the money to pay you and you sue him, and you win (which it isn't clear that you would win) he still doesn't have the money to pay you.