Yes most Bank's have Safe Deposit boxes available for rent. However, you will find that all in Hua Hin are full at the present and you will have to join the waiting list to get one.
Depends what you want to store. There are some hotels and guesy houses that have safes that would let you use them if you are not a resident for a small fee.
[color=blue][size=134]Care in the community success story.[/size][/color]