The border is open from 06:00 to 22:00 daily.
To get from the Nong Khai bus station (map location: mmm) to the Friendship Bridge Border Crossing, tuk-tuks charge around 100 baht.
The Thai exit is simple and quick. After getting the exit stamp, there is a bus to shuttle people across the bridge to the Lao side for 20 baht. Walking across is not allowed.
The Laos visa on arrival requires several similar forms to be filled out and a payment of 1500 baht or 35 USD. They give out the forms from office. Once the forms are ready, the process is fairly quick and the lines are short. They just take a quick photo and then take the payment, passports, and papers and process them in bulk inside the office. Once a passport has been processed and stamped, it comes out the other side at another window where everyone is waiting.
There are currency exchange offices on the Lao side of the border. They open around 08:30 or 09:00. There may be one or two open a little earlier.
There are mobs of motorcycle taxi, tuk-tuk and truck taxi drivers that will start harassing people as they are going through immigration. The fare to downtown Vientiane is around 40K kip minimum.