Udon Thani is near the border with Laos. It's a large city, with lots to do when compared with other Northeast cities. There's a KFC, and maybe a Starbucks (soon?). But generally, it is a lot more comfortable for foreigners, while still seeming quiet and relaxed compared to Bangkok.
Those bottles are filled with gas. You don't see a lot of big gas stations over here, except maybe on the main highways. For people just filling up thier motorcycle (scooter), they only need a litre or so, and it makes sense to buy gas from roadside vendors this way.