If you have a dance captain, or a choreographer who's going to be around for the whole production, you don't have to be as specific with your blocking notes. I happen to be pretty good at writing down choreography, so I tend to do it...if I'm there when they block it. Especially if you're working off a cd or something, you can help keep track that they're not blocking the same section 2 different ways (trust me, it happens).
If you're seeing it later, you can add in the "bigger picture" moments to your script like...big travel SL, claps start, or shuffle step. Especially useful is to write down whatever terms THEY use to call things, so that you know if they want to take it from the "lift combo" that means measure 89 or whatever.
I tend to write dancer counts in either my blocking page of the script or make the actual script out of dancer counts (takes less room than calling off music, and if you happen to not read music I've been able to teach many people to call this way rather than learning to actually read music). So a song with a 16 count intro and then a held note a little after they start singing would look something like this:
1 2 3 4 5 6 7 8
2 2 3 4 5 6 7 8
THEY SING THEN HOLD THIS NOTE OUT 2 3 4
Then if they have a lot of choreography in that 16 counts, you can write an individual move for each beat if needed....I tend to put X's for claps. "BC" for ball change...a turning arrow or an infinity sign for a turn...whatever works for you.
The numbers for music beats is especially helpful to me for calling a show, so I can always call on exactly the right beat, and as I said, takes much less room than the actual music. Though I have also cut-and-pasted music into the script if it's easier to read a section that way.
I'd also recommend making several full-page size groundplans of the set and having blanks of those available. It's great to quickly jot down everyone's position for new sections of a big group number. Easiest for chorus is to just write in their initials where they stand - but take time ahead of rehearsal to make sure no one has the same initials and you have ways of differentiating those people!
Hope this helps.
Erin