Is that legal?

I don't see why it wouldn't be - seems easier to just put your trash where it is supposed to go.

I live in Missouri and not sure if there is any laws to protect us renters.

Is this charge in reference to you moving out?

I am wondering if I have legal ground to sue both parties (former roommate and landlord) for undue stress?

Did the management company agree to cancel the lease?

Can they refuse my lease due to lack of my SSN

Providing an SSN is very, very common in the real estate/renting business.

Does leaky wall and toilet pipe that landlord will not fix make a house unliveable?

Are you referring to a breach of the warranty of habitability?

If you're under medical supervision and physically not capable to lift or move HOW DO YOU Comply to a 30 day notice to Vacate?

The surgery has no bearing on the notice to vacate - you will need to ask a friend to help or enlist a moving company.

Was homeowner in breach by NOT providing a heated pool as specified in listing and rented knowing there was a huge bug problem.

You definitely should contact everyone involved and request a refund at least.

Can I get my money back in small claim court?

Unfortunately it does seem like it would cost you more to get the $310 then it would be worth.

You should contact the electric company for an explanation as to what goes to your meter.

When they re-rent the unit, could we demand an early termination fee refund (minus ACTUAL damages) under RCW 59.18.285?

The facts do indicate that the LL is not cooperating with the mitigation efforts.