Validity of Guarantee

That is not is limitation act as the bank gurantee is limited to term and terminates upon the Gurantee and Gurantor's mutual agreement.

Yes. The guarantee gets valid until the agreement of borrower gets revoked by any means by the banker.

that depends on the form of guarantee.  If it is continuing guarantee, the limitation is diferent. and there will be caluses that whenever the original borrower acknowledges the liability, the guarantee also continues.  It all can be siad by looking to the forms of guaranteee and the agreement between the original bowrrower and the lender