Laos forum

The easiest mode of transport to hop/step in and out of is probably songthaew. I chartered one from Udon directly to the bridge for 600 baht, which saves you dealing with yet another bus station and more transfers. The tough bit might be eeking your way through the queues waiting to get stamped out of Thailand and Laos visa/entry, and also I think there's only the 20 baht bus option going over the bridge itself. Anyway just literally hop on/off that then there are always tuk tuks/songthaews going the 20km to Talat Sao in Vientiane for about 50 baht/person (or private car for 300-400b takes you directly to your friend's place).

#2:
The tough bit might be eeking your way through the queues waiting to get stamped out of Thailand and Laos visa/entry

agree. the queues can be long - best if you can avoid weekends & public holidays. even though the lanes are reasonably wide, people just fill the space in between queues during busy hours.

for the Thai-Lao International buses that #3 mentioned:
you'll have to go to the bus station closest to Charoensri Mall (not sure if the name has changed) in Udon Thani (the city has at least 3 bus stations). just outside of the UTH airport arrival hall you can buy a fixed fare coupon for a shared van that will drop you wherever you want within Udon Thani city.

going in the Thailand>Laos direction, they usually allow only foreigners who already have a pre-arranged visa for Laos or come from countries that enjoy visa exemption to buy tickets. at Udon Thani bus station they can be quite strict, insisting on checking your passport before they will sell you a ticket. no such problem when taking these buses in the Laos>Thailand direction. you'll still have to alight at both the Thai immigration & Lao immigration but the advantage of this bus is that you can leave all your bags on board (of course don't leave any valuables in them). timetables for these buses are near the bottom of this page:
http://laomeow.blogspot.com/2008/07/bussongthaew-schedulesdetails.html
more up to date timetables for the Vientiane>Thailand direction are here:
http://laomeow.blogspot.com/2010/01/vientiane-khua-din-bus-station.html
again, these buses can be packed on weekends so you might have to wait for a later departure to get a proper seat.

btw in 2007 & 2008, when arriving at the Lao immigration on weekends, one had to squeeze to the front on the queue in order to get a copy of the immigration arrival form from the immigration officer, & then squeeze to the back to fill out the form & join the queue proper...this was because some guys would take all available forms to sell them. when hunting for the forms, the immigration officers directed me to those forms-for-sale guys...on another visit i was pointed to those guys again, but when i asked nicely in English an immigration officer grabbed a form from those guys & gave it to me for free to those who've been there recently, what is the situation like now?

Flying is indeed a good option. was travelling for 5 months on crutches as well, after a while you get used to it and just do the same as everybody else does.
though have to agree that you need to be careful with your knee (had to learn how to walk again after the surgery, took me a month).

as for captain_bob, 600 baht to take you from Udon to de bridge for Laos is way too expensive.
I always took the local bus in the center of Udon (not even at the bus station) for 35 baht and You can get off at Tesco Lotus in Nong Khai and take a tuk tuk there to the border for about 40 baht. so that saves you about 525 baht .
The queues at the border can be a hassle, just try to go at 8 in the morning during a weekday and you'll be fine.
Good luck with the injury man, I know it can be hard but don't let that waste your trip, still keep enjoying it!