The first answer - is when we play - whether we are playing at writing a story book, playing outdoors, playing with craft materials or musical instruments, what ever medium we use, our brainwaves are at a perfect state to absorb information and create neural pathways to develop.... and that is GOOD!
The answer to the second questions is I do not know.... because there is no way of knowing what your child needs to know for a career that they are undecided upon and may not even exist at this current point in time (so in reality - they can not be schooled for it yet).
What your child needs is good life skills, good interpersonal skills, good creativity, and an ability to play with ideas (do you get why play is so important ;) )
Then you also need to consider, who gets paid more .... footballers playing their favourite game, or someone locked in an office all day.... having spent their whole life studying .... interesting thoughts .... let your children thrive at what they are enjoying, and encourage good life and foundation skills.
Children need to be children - then they will be confident adults ... something the education system has lost sight of.