Bangladeshi passport holders are eligible for DTV?

Hi,

I am thinking of applying from Vietnam. I am a US citizen with a American Passport wanting to apply for DTV for medical treatment. My husband and 2 children (3 years and 4 months old) are Bangladeshi passport holders. Will they be eligible for the spouse and children DTV visa? I will be the primary visa holder. How long will the total process be for myself and my family to get the visa if i apply from Vietnam? Will it be quicker in any other country?

I am currently holding Bridging visa A in Australia. I want to visit thailand as a tourist in April. Am I eligible to apply for Thai visa at this moment ?

Moreover, I am currently unemployed. Will they reject my visa application for this ?

P.s I hold Bangladeshi passport.

I need some info that If I travel Cambodia with Bangladeshi pp via Thailand n want a reentry visa( from Airport),will there be any hassle if I want to travel Cambodia by road?