A. Execution of Rent Agreement between House owner and Firm (Partnership Firm) by representing through its Authorized Partners is permissible in the eyes of law. However, you have to check the Partnership Deed as to whether the authorized person duly authorized by the other partners or not? and Whether the Partnership deed is registered or not as per the Indian Partnership Act?
B. As I said, owner or GPA holder of the owner of the house can enter into rent agreement. Moreover, the payment of stamp duty is different to state to state. However, according to sources, 1.5% stamp duty on average annual rent till 5 years and 3% is applicable is more than 5 years.
C. Attestation of notary is optional. No registration is required below one year. Or License agreement can be execute instead of Lease cum rent agreement.