What should I know before going to the Thai embassy in Vientiane for my tourist visa appointment?

It is my first time getting a tourist visa ever in Vientiane, and I just read the fine print disclaimer of the email they sent me, with my confirmation and number appointment, and it says to dress appropriately and that you must not wear tank tops or have bare feet.

So I have a few questions which are:

1 - flip flops okay for shoes?

2 - do I need to buy a t’shirt before my appointment tomorrow? (Did not bring any clothes with me that cover my shoulders or have covered shoes!)

3 - my queue number is 130 do people recommend getting there early when they open or later around 9.30?; and

4 - can you photocopy your passport there at the embassy. I have my photos ready and other documents printed if they ask, just no copies of my passport. I read that you can photocopy there, and can pay in baht for it.

Thank you 🙏