An idiom for bonding is "spending quality time together." Or, "Let's stick together."
cooperative
This is not an idiom. It means just what it sounds like -- remain together in a group instead of separating.
The phrase "pull myself together" is an idiom.
The sentence is not, because an idiom is usually a phrase. The idiom is "do lunch," which means to have lunch together, usually while discussing business.
Yes because you are not literally hitting a sack.
To figure somrthing out from the information avaiable
adds up, makes sense
Do what ever you want to do.
Don't go bananas when I tell you what I know.
It means to go faster
it means go to sleep