Landlord Tenant

Can I give a notice to quit to my tenant's brother?
I need my tenant to leave the house so that I can let my friend stay there. But the problem is that my tenant is out on a business tour, and at present, it is only his brother staying at the house. Is it enough if I give the notice to quit to the tenant’s brother? I live in District of Columbia.
What should a tenant do upon receiving a lawsuit notice for eviction?
What should a tenant do if he receives any notice of lawsuit related to recovery of possession of the leased house where he resides with family?
Does accepting rent after lease expiration renew the lease in California?
My lease got expired two months back, but I still stay in the house and even pay the rent. My landlord is a nice guy and has no issues till now. Does the acceptance of rental payments imply that the lease has been renewed? I need to know the relevant California law on this.
Is it necessary to repair floors before renting a house in California?
I need to do get new floor tiles for all the rooms. My friend suggests me to first do the flooring work and then rent the house, because if the floors are not in good condition, the house may be regarded as untenantable under California law. Is that true?
Can my landlord terminate the lease after accepting late rent?
After accepting my late rental payment, my landlord is now threatening to terminate the tenancy contract. Can he terminate the contract after accepting my late rent?