hello and welcome C: (I've never been to the con either, but I've done alot of research ^.^)
It does cost money for a badge (basically a ticket for the con), I know that it's $30.00 for a pre-registration badge (and most of the stuff you need to know IS on the website so you should probably look at that)
If you stay in the hotel that's when things start getting a bit spendy, but if you have family/friends in the portland/vancouver area that can help cut costs.
And as an answer to your second question YES LOTS of people cosplay
. And lots of people don't cosplay as well, it's all great fun ^.^
I'm sure some other people will post on here giving you better information. c: