I love Chowderfest. We usually go every year. I have never had trouble getting tickets. (You can get them online.) It does get croweded, but there's always plenty of parking around Bay Village and they also run shuttles from other parking locations. We have a place on LBI so I can't recommend lodging, but there are plenty of places on LBI that have off-season rates.
The "Merchants Mart" is on Saturday -- bascially an area under tents with all sorts of vendors. Sunday is the Chowder cook-off.
It is a rain or shine event -- it rained last year off and on Saturday -- so just come with ponchos and have fun!