You can extend when you have under 30 days remaining I believe. They will stamp you in for 30 days after the "leave by" date, regardless. Bring 1900 baht, TM.7 form, and I believe passport copies.
There's also a green bus from the border to downtown Vientiane bus station about 1 km. from the consulate. Additionally, there are busses that leave from the bus station to the border frequently and all the way to downtown Udon Thani. I've found that much cheaper than taxis if cost is a problem.
I was just there Monday. You need two passport photos (2.5x3.5 inches I believe, a smaller size) with white background, a copy of the photo page of your passport, a copy of your Laos visa, and a copy of your Laos entry stamp. The consulate has application forms. You can do that at the consulate for 5 baht/copy. You don't need anything else.
A flight out of Thailand and 20,000 baht cash would be good to have when entering Thailand, but Nong Khai land border is easy, I (and others) never have needed to show any of that. Arriving to Thailand by air may be stricter depending on the IO.
As others say, turn in form before 11:30am, pick up between 1:30-4pm the next day. The order for pickup depends on the order of drop-off.
Hi all, had no problems. Not sure if you could come anytime for pick up, but my number wasn't called until 15:50. As usual, trip to VTE was smooth and easy, nothing new, so I won't make a full post about it. As always, I appreciate the help much!