I would get very aggressive with them for even threatening to keep my deposit.

He first started raising his voice and threatened to dig up the concrete that his guys supposedly poured around each post extending one foot below the frostline...as I reminded him of the code, and throw it through the windows.

I act above board and carry good insurance but have never been sued or even threatened to be sued. 

You should understand the process so you can blow their mind when they threaten you and you tell them what they must do.

Squatter is threatening to call social services because she isn't allowed to use the kitchen.

A last resort would be to take photos of the "code issues" and then threaten to take the landlord to small claims court to get the deposit back on the grounds the unit is not satisfactory.

It really depends on the relationship you have with your tenant...have you been threatening eviction...getting into arguments...if so..your chances of getting any money may have ended...I have been successful putting some tenants on payment plans for two months if they are going through a rough time and they have ended up working pretty hard to get current...but that just depends on the tenant...I even had one lady go to the State for assistance to pay rent for a month...and they did!

So if your tenant cares about getting their money from section 8 then they will pay their share of the rent ON TIME.Or rather than taking your complaint to section 8, your friend can simply threaten the tenant and inform them you plan on taking your complaint to section 8.

The tenants threaten to sue, and I contacted a lawyer, who's also a family friend.

Then said homeowner threatens legal action for no permits when you do the job to roughly 85% completion and he refuses to pay the remaining 40% of the bill.