That's right, they do send the numbers.
They use to send HP numbers as well, but changed with Velious cause of the new 32k+ hps on the mobs. Just couldn't fit that number into there, so they shrank the packet, and put only %'s in now.
Player HPs you get full, but the UI only allows us to use Percentage.
I have yet to see any evidence of the ability to get group member's mana. Not even the %, thus why it currently isn't in game. Who knows, they might add that in soon. Hopefully.