Agree with #5 & #6 ... have used sorya extensively over the years, albeit on more heavily-traveled routes. yes, the buses are older and clunkier, but they're also cheap and frequent.
In all these years, I've yet to meet a bus driver or attendant or a sorya bus who actually understood english ... the affirmations of "going to pakse" may have been a manifestation of that asian habit of just nodding and saying "yes, sir; yes, sir" when they have no idea what you're asking ... ... ...
As for what's printed on the ticket itself, same as what maneki asked: where did you purchase the ticket from?
#7: There are a couple of local pick-ups that do a run to pakse every 2nd day, departs from the under the western-side pylons of the japanese bridge.