I would be prepared to split up. Some attractions may allow you to stay together, but I would not expect it across the board. The card is still intended for the person who needs it and 5 others.
Yes, I agree.
If your party total is 7, you may have luck with them 'stretching' the number. If 10, not so much.
For attractions where you would be using Mainstream Lines, there is no limit to the number of people since you are in the regular line anyway.
If you want to stay together, I would suggest using Fastpasses and a touring plan would be your best bet to reliably stay together. You don't have to follow a touring plan religiously/exactly, but you want to be in the least busy places in the least busy park.
Even during Easter, it is possible to walk right on many attractions if you know when to be there - not the highest demand ones, like Toy Story Mania, but many others. If you are at Fantasyland in the first 2 hours that the park is open, you can walk right on many attractions with a 5-10 minute wait.
Smart phone apps can help you too. If you have Verizon, they have an official Disney app called Mobile Magic, which is actually tied in with the park system so gives the actual posted wait times. (not available yet for iPhone).
There are some others from places
undercover tourist that also have pretty accurate wait times.
Many people find doing those things are more helpful to them than using a GAC because it is more predictable and helps you to keep larger groups together without having to worry about whether it will be allowed as an exception or not.