I can't help you for food or lodgings since when I lived in the Eastern Townships I lived in a university dorm, but one of the best things you can do while you're there is climb Mount Orford. It's a great day and an amazing view at the top. posted by GilvearSt at 2:35 PM on July 8, 2012
I'd try asking your question on the chowhound Quebec board for restaurant suggestions. I know that Owl's Bread in Magog and Mansonville is very popular. I don't think you'll have a hard time finding great vegetarian food. There are a lot of local farms nearby and therefore restaurants that specialize in seasonal and local produce. Ayer's Cliff is a nice town and Lac Brome is beautiful.
As far as lodging goes, there are a number of spas in the area that also have lodging. One of the most popular (and expensive) is Spa Eastman. I have also heard great things about Spa Ofuro. If you sign up for some of the daily deal websites in Quebec (ilovemtl.ca, groupon.ca, etc.) they often have hotel/spa deals for the Eastern Townships. posted by picklebird at 5:35 PM on July 8, 2012
oh yeah. go to Jardins Sauvages, a restaurant based on wildcrafting and gardening. apparently the cook does insanely delicious things with vegetables. posted by andreapandrea at 6:54 PM on July 8, 2012
posted by GilvearSt at 2:35 PM on July 8, 2012