Time for the ex-Diz cast memeber to jump in.
No group rate tickets. The only discount tickets they sell are multi-day tickets, which won't work in this case. It's possible that policy has changed since I worked there, but not likely. They don't generally do that. The way the "free passes" work is everyone that is part time and above gets what's called a "main gate" pass, which gets them 4 or 5 (depends on how many people are in their family) free admissions X amount of times a year. When I was there it was 12 times a year, but they may have changed it in 5 years. The down side to this is that pass can only be used once per day. So, if you've got 2 people that want to get in and 2 people coming later on, you'd have to wait for the late people, otherwise only 2 people were getting in. Clear as mud?
Periodically, they give away free tickets that you can give to friends (not sell on eBay or on the street! They pay people to find those) that are good for one day. Now, the GOOD news about the free passes (and the main gate) is you can go back and forth between the parks without buying another ticket.
If you're looking for meeting space AT Disneyland, best bet is probably the Disneyland Hotel, the Grand Californian or that other one I can't remember the name of. There are plenty of hotels RIGHT outside of Disneyland (hence the reason Walt Disney World is insanely huge) that probably have cheaper meeting space rates.
I'd love to make this one, but it's not likely. If it were in Orlando, I'd make come hell or high water since I'm jonesing for a Disney fix like you wouldn't believe.....