Jomtien immigration accepts fixed deposit accounts. I use Bangkok Bank (the orange bank book, not the blue one). Receiving interest once per year on the day of the initial deposit.
As long as your Philippines DL is not the temporary one, you are legally allowed to drive in Thailand. There is a specific agreement among ASEAN countries.
No need for an international license... But the brown helmets on the streets may not know about this agreement.
I have friends in Hua Hin, they mentioned on several occasions that their local immigration office is very helpful. You can probably get your retirement Visas without an Agent. But much can change in 3 years.
If you want to alter between Bangkok and HH, I would think it's better to get the visa in HH.
I assume you have been to Thailand before and been to the various places that are popular with retirees and also decided where to settle.
If yes, it's best to join Facebook groups for these areas to get a feel of the local Expat community and their general advice on the immigration office and agents in that area.
If you haven't been to Thailand, don't worry about Visas. Get on a plane and come here for 1-2 Months to see for yourself if Thailand is the right place for you.