Most jurisdictions don't have any restrictions on whether a landlord can rent, while in many other jurisdictions a landlord may have to have a permit or license to rent out. Check with your city or county to see what is applicable.
Most jurisdictions have strict rules regarding legal rentals. You can check with code enforcement in your town to determine if the apartment is legal.
A landlord cannot legally harass you for rent if your rent is not in arrears.
First, you must check with your current landlord if it is in your contract whether or not you are legally allowed to rent out your apartment or not. If so, then you must check if there is a fee you must pay to your landlord or not.
Never!!
Absolutely.
Why not? Even family members can rent to one another.
Yes, no matter if your lease states it or not, the landlord can legally do this if you're behind on rent.
Physical damage, or non-payment of rent.
No, the lender can not legally penalize the landlord, the borrower, if the landlord chooses to rent to tenants with low credit scores. Consult an attorney for details.
Generally, the landlord should not be getting rent from two tenants at the same time for the same unit.
A landlord may legally evict any time you are late with the rent. Even if you are just one day late one time.
Legally, in the United States, lot rent can only be raised by $200.00 at one time. However, there is no limit as to how much a landlord can raise rent per year.
If your friends landlord lowered the rent for him/her and then after moving in with him/her, he/she decides to move out, then the landlord will most likely raise the rent again.