My bf is Lao and I have been to the country several times with him. When we go we fly from BKK with Air Asia to Udon Thani (cost 2600B rtn). Then take a minibus from the airport to the border (new minibuses and 100B cost each). Go through Thai immigration and get another minibus to Laos immigration (5 mins). Then at the other side of Laos immigration get a taxi or tuk tuk to the town centre (100B).
When I flew direct (one time only) it was with Thai. Cost was 10500 Baht rtn and I was waiting in a queue for 90 mins to go through immigration and get my VOA. Going through the land boarder is much easier and quicker, 20 mins only.
If you are going to spend anytime in Vientiane I would suggest the land crossing. It is much cheaper. Then fly Lao to LP from Vientiane. You can always fly back from LB directly to BKK if you want.
As for travel agents etc, I have no idea as I have my own personal guide

English is not a widely spoken as in Thailand, but you will find it spoken quite a lot in LP, and there now is more and more farang opening up in business there (Laos), doing bars and restaurants. Laos is becoming more and more investor friendly. See this link in todays Bangkok Post [url=http://www.bangkokpost.com/Business/16Jun2007_focus03.php ]www.bangkokpost.com/Business/16Jun2007_focus03.php [/url]