No dont stress...i always see people running to get to the consulate...its takes a bout 35mins from thai border to consulate and about 5mins to lodge application. U need to have a photo to give the laos border entry as well.
The Avalon is a good hotel..there isnt much to do in savannahket. Need wifes house book and id card copy and marriager certificate. There are some people u can pay 100 baht to and they fill out the paper work for u out the front of the consulate.