1) There are NO money changing facilities at the border. Get your dollars beforehand!
2) You get the Laos visa at the border within 10 minutes - one photo required, or a 1 $ surcharge. You can also get the visa beforehand in Bangkok - same day processing for an "express fee", which is similar to what you pay at the border.
3) Thai visa. They do insist on the pics.
4) You can still get to Vientiane for 100 bt by tuk-tuk, or much less by public transport.