bob jenkins wroteNFHS rules (but I'd be interested in other codes).
Team B likes to "cheer" before each point. This "cheer" consists of the players on the floor, as a group, yelling "Spartans!" (once) followed by a single clap-and-simultaneous-foot-stomp.
If not unsporting, then there's no issue. I don't immediately see a problem here.
Any issues if this is done before the beckon for Team A's serve?
Again, not that I can see.
After the beckon but before A starts any action related to the serve?
Nope.
While Team A is "in the act" of serving?
If you deem it an attempt to distract the server, yes. If not, no. Teams are not necessarily required to be silent while the server serves.
What if it's Team B that's serving in the above situations?
If you deem it unsporting, rule it so. If not, don't.
Sometimes use the other team's reaction as a guide to yours. If they have zero problem with it, sometimes you need to just go with the flow.