Will I be asked for proof of funds or onward travel during my 1st SETV appointment in Vientiane?

Yes 1,000B

There is a place to do copies right there, or you can do them slightly cheaper if you do them yourself beforehand. Submitting in particular they are quite quick, it shouldn't take that long. Before they did the appointment system a number 400, 600 would not be unusual. And from what I have read, it is possible that not all numbers actually show up, there may not be 90 people before you.

They may want a copy of your Laos visa and entry stamp so do the copies after you get there.

@Charles ********

And the application form of course! Of course, if I'm wrong, I hope the mods or others chime in.