Unfortunately, the new owner can raise the rent to any amount he wants. Of course, the current tenant can try to work with the new landlord to see...

Hire an attorney to begin the eviction process as it appears the lease has been breached if anyone other than the signed tenant(s) are residing there.

not grounds for early termination of a lease agreement, but certainly request immediate cleaning of the carpets and all floors.

A landlord can appoint any person to act as their agent at an eviction hearing with or without a power of attorney to do so.

if you had a verbal agreement to pay him rent, then yes, you could be found liable to pay. You do not have to have a signed rental agreement.

There is a process you must go through with the landlord prior to breaking the lease without penalty. Best to discuss with a landlord/tenant...

No. A lease is a contract and without a valid exemtion as outlined in the Texas Property Code, then you are bound by the terms of the lease. Try...

Yes, you do but you must follow procedures that are required in Texas. Best to consult with a landlord/tenant attorney for further guidance.

if you prove you were never served with the 3 day notice then they will just have to start all over again; eventually, you will be evicted if you...

That would be up to the landlord. Most landlords will go through with the eviction proceeding and get a money judgment against you for the amount...