You could ask this in the general chat, too. ^^
I've never been to Anime Boston, but the general stuff that happens at each con is usually the same.
Everything you asked generally happens. Some cons have hundreds of people, so god knows what some of them are doing. :P
Well, except for the cliques part.. I hope that doesn't happen.
You could try looking through convention reports, and read up on what they did. ^^ Widya's Anime Convention Link page helps with this..
Just try to find personal reports and... yeah. ^_^
Most people just go to meet new people, watch anime, share their music videos or art, and so on..