Letter of Intent not commonly used in room or unit renting. That is for larger scale rental say the whole floor in an office block or properties purchases. For unit or room rental, put down deposit then done deal already.

First deposit mostly by cash, or cheque if the properties are rented by companies for their staff. Your agent will give you a receipt, that should be sufficient. Future rental some prefer internet banking for records and minimum effort for rental income.

The person who want the agreement to be stamped pay the money. Normally agreement is not stamped even with agents, no?