What do these blocks report and how can they be used?
I don't know where you got those blocks. I checked the libraries and I don't see anything with those so I cannot help you.
those are blocks we use to debug the internals Snap! in dev mode. They don't do anything interesting or useful for user projects, that's why you're not seeing them in user mode. It's not that we're hiding a secret from you, or that they're somehow "advanced", they're not.
Yes they do.
if(processes>100):
run jsf alert("Laggy!")
frames report the fps the project is running at, stack size reports the stack stack size of the script the reporter is in, the processes reports how many scripts are running at the current time.