I don’t think they will ask you. Thai Consulate in Vientiane has generally been said to require less than other Consulates. Others will reply if they were asked for bank statements for ED visa but generally the answer for Vientiane is no.
I went to Vientiane for ED visa in January. You have to spend at least one night there, as you turn in application in the morning before 11am and must pick it up the following afternoon. What questions do you have in regards to the process? I’m happy to help, and there are a lot of previous posts from others with experience.
Unfortunately since they have little competition in town (no competition?) their customer service isn’t great. It was nice to be with a group, but we were all sometimes confused about the process, together. One Korean girl in our group left Laos without getting a stamp out, and had to go back. The Aya staff are minimally helpful on what you need to do/which forms you need. They helped us get to front of lines. But otherwise were just there for transport. I saw some other higher end groups that had agents do everything for them (photocopies, standing in line) and they included a nice accommodation. I don’t think that would be worth it though. If I ever had to do it again, I would do it on my now that I know where to go. Aya goes Sunday night to be at Consulate Monday morning, which is the busiest day of the week. I’d go on my own a different day.
Ok, then I can answer your question! I took Aya Bus Service in January from Chiang Mai. They are the cheapest in town, and they only take you there and back, you have to get your own accommodations.