Are there any special celebrations in Vientiane for the October full moon? That would be 26 or 27 October, I'm not sure which. Many Thai towns have boat races on the Mekong; maybe Vientiane does too? or something else?

Pha That Luang Festival - 26th till 31st
Held in and around That Luang stupa, the national symbol of Laos, where hundreds of monks gather to accept alms and floral votives from the people; the festival includes a grand fireworks display at night.

Sorry...Boon That Luang isn't until November 10th, the boat races ( Boon Song Heua) are on the 26 and 27th. The Mekong river front is jammed with booths, carnival games, restaurants,etc... right now

26th is Boun Ok Phansa, end of rains retreat for monks. there will be the usual morning sermon + offerings & evening 'wien tien' i think. Isan side will be parading their prasatpeung (yellow wax castle sculptures) around town, not sure if Vientiane will do it at the same time or wait until the Boun That Luang procession...need to ask.

#2,
Guide books and websites mentioned that the That Luang festival last for a week and ended with music, dance and lasershows and fireworks. Do you know if this happens every night or only the first or last night ? Do you know if the full moon night is the first day or the last day of the festival ?