Self employed business owners provide a contract for themselves and letter giving permission to work remotely. Need to provide your business registration info
In Vietnam. You can be approved with non seasoned funds. There are many posts of approval to confirm this. Funds must be in a personal account, make a relevant transfer and then apply.
They are looking for a current remote work contract, freelance or permanent is fine. You do not need to have been a freelancer to get the DTV, just demonstrate how you will be working remotely in Thailand and with non-Thai clients/businesses.