Porn Stars
For those people who can't travel to LV, Exxxotica is a great convention to go to. I've met plenty of stars there, and it's been a lot of fun. I even made a few "special" contacts there.
It's true that there are long lines for some of the stars... but it's usually worth it. Sasha Grey is one of the warmest and friendliest stars there and I really, really, really, wish she'd provide but it's not likely to ever happen. Ok, maybe if you're rich like Charlie Sheen. 
Yes, the stars charge for their photos... and this is common at most conventions even the non-porn ones. I'm told that the reason the porn stars don't do it for AVN is because their production companies pay the costs for that convention because it's an industry convention.
Exxxotica is more a fan convention, although this year there are specific industry hours. However, most of them don't charge for pictures with your digital camera, and they don't charge for the autograph so if you bring a dvd, magazine or something you can get the autograph for free. Probably. But the main reason why there are costs for pictures at Exxxotica is because of the huge expense of making large quantities of professional photographs and then shipping them to the site and making sure that they arrive on time and undamaged. Also, the stars have more travel expenses (it costs more to get to NJ from LA than to get to LV), hotel expenses, food expenses, clothing, etc. It really costs a lot for the stars to attend. If a big company like Genesis or Penthouse is sponsoring them, the costs might be less. Several stars have told me that they wouldn't attend Exxxotica if a company didn't sponsor them but they'd go to AVN even without the sponsorship.
Remember, for the stars, this isn't a "meet the fans" event, it's a business event. It's an opportunity to promote their films and websites, and other projects. Meeting the fans, signing autographs, etc,. is just a part of why they are there. They are really there to make money. Period. If a production company doesn't cover their costs, they have to get that money back from somewhere so they do it through picture sales, dvd sales, etc. I know several stars who were there the first year that didn't return the second year because they didn't cover their costs. It's not worth it to them.
Btw, I don't think Bree Olson will be at Exxxotica this year... according to her website, she's dancing in Pittsburgh that weekend. That's a real shame... but according to the list on the show's website there will be a bunch of stars there this year that haven't been there. I'm really looking forward to meeting Nina Hartley who is a porn legend. There are also a few newer ladies like Amy Brooke that I'm hoping to meet and chat with.
As for the after parties... most of them are in local clubs. I think I've posted some of this info in the past (the "search" tool is your friend) but from what I remember from last year, there were parties in two of the strip clubs in NYC, and at The Harem in Lodi, NJ. It'll probably be the same this year. No way to tell which stars will be at which club at this point... but last year the majority were in NYC because that's where their hotels were.
Hope this info is helpful.