As far as how much for each character -
My main characters, as you can imagine, will be very understandable by the time you get through the game. If you play through all three POVs, you're looking at quite a bit of description both internal (when you are that POV) and external (when you're one of the other ones).
The older brother and older sister each have three romantic paths you can follow, and each of those folks gets attention both from the POV you're playing, and from the other two POVs who notice you with the first POV. That's where my planning got tricky, because if you're POV 1 with romance path 1, who do you see POV 2 with? How does that impact path 1 versus path 2? And so on. For the third POV, you have a lot of "what's really" going on being explained, as well as the actual climax of the story.
For the supporting characters, you do get some development, They are more than "cardboard cutouts". I'd say that based on how the script is going so far, the least among them has twice as many lines as Julie ended up with in SY.
Also wanted to mention that it looks like Agata Maria will be doing the character art for Camp Handiba. You can get a sense of the style by going to the artist website:
http://artwanted.com/artist.cfm?artid=22306
Thanks again for the suggestions and continued interest!