embassy love photo taking from phone, if you have local newspaper with date as a back ground of passport photo ,it will help verify that your picture is uptodate
sometime they just ask for supporting document that you have plan to support your self in thailand.
If you have evidence that you have income from stock dividend, pension or just rich parents you should be prepared to submit those document when asked.
if you do not have such evidence you should have some plan to tell embassy how to support your self for 5 years.
This is not formal requirement but if the embassy just curious and you do not have supporting evidence your visa will be rejected
some embassy will ask for cancellation of current visa first before approving a new one.
But for some embassy, they can process new visa right away without having to cancel the old visa.
This happen in the past.The rules keep changing from time to time and each embassy have different rules and process.
The recommendation we give to our customer is that if you are unsure about the success of getting DTV please do not cancel their current visa. They should apply for dtv when the current visa is almost expired.
You cannot activate DTV visa inside a country, it is only for extension.
But the rules might change all the time, the immigration officer might confused and stamp it for you.
Anything can happen in thailand where rules and regualtion are not clearly stated
1. you can fill random stuff(this is standard form for people who apply for short term tourist visa so they will ask some questions that doesnt make sense for long term visa like dtv
2. You can enter thailand later than 3 months, no penalty. nothing to worry
thai immigration doesnt have any official guidance about this. Even if they has, they will only have it in thai(which is a confidential document circurate internally)
If you get DTV, you will have to reentry thailand again and show the immigration officer that you have dtv visa(from your email)
Then the immigration office will stamp your passport and put your entry date in their computer.
At that point your dtv visa is activated.
Normally , when you are issued a new visa, the old visa(retirement visa) will get cancelled automatically.
so if you are not activate dtv visa by reenter thailand , you might get penalty for overstaying in thailand.