To be honest, i don't think i'd limit the starting BP unless you were indeed going for a low-powered game. Just because someone is 16, doesn't mean they can't be skilled, smart, or physically adept. Hell, i've known plenty of teenagers in high school who played sports, were on the swim team, took martial arts, or just biked/were active alot. And they were probably much more physically adept than most adults i knew at the time. I know i was much more healthy/active as a kid than i am now, closing on 30.
Now, granted, every 16 year old won't be maxed out in several skills, so perhaps i could see a realistic cap there(1 at 5, rest at 3 or less, or 2 at 4, rest at 3 or less, groups limited to 3.) That way you could have that odd fellow who trained in fighting from when he was young, reaching black belt at 16(and it happens, ive known several) or that genius computer whiz lady whose been tinkering with the stuff from as soon as she could walk, and knows her way around anything electronic.
Perhaps Aptitude could stick a skill at 6 to start(of course allowing a 7 later on.)
As for limitations, i'd point that in the direction of what kind of campaign. If they are more street/lower-middle class kids, limit it more around 8. If they are rich kids being groomed for the corporate world, then leave as is. For middle class, hover it around 10.
Cyberware would be well touchy, as the stuff you could grow out of would be pretty much...well, highly suggested you dont touch until you're done growing. I think eyes and the like could work, since the skull is about done growing, as other headware, and possibly even wired reflexes. Bone lacing, however, could hurt like hell.

Im not sure about hand razors. At 16 they are unlikely to grow TOO much more, but still.
Bioware, however, i'd say would be doable, depending on the campaign type, if they have enough cash.
To be honest, in a type of world that is Shadowrun, i'd think 16 about means ''Man of the House'' in some cases.