I'm not sure I can fully answer your question, but I've been playing for two years.
I'm not sure if you will automatically have an intake of youth players. But I'm guessing that you will get an intake for sure if you have at least one scout, a youth team coach, and an assistant manager. As far as my experience has gone, usually lacking an assistant manager or a scout will disable some team features (like weeding out unrealistic transfer and loan targets). I'm not sure about lacking a youth coach. I'd advise hiring one as a cheap free agent and seeing what happens next season.
As for the 20 youth and attack coaching, they have anything to do with your youth player intake (including type or quality of player). Those stats are for training and development purposes. Check under >View Club>Information>Facilities>Youth Recruitment Network, and see what the statistic says. That seems to determine the quality (and variety of nationality) that your club will intake. In general, the youth players will suck, even when you have a great club with "Established" for youth recruitment. They will only occasionally have more than a couple stars of potential, although currently as Zaragoza I've taken in three wunderkids in two seasons! Just watch for those gems, and make sure your assistant has some decent "judging player potential" stats. He will generally point out the good players.
Run a google search for "coach calculator" to play around with the stats and see how they affect training if you like. Essentially "determination," "level of discipline," "motivating," and "man management" are the essentials along with one high rating in either "technical," "tactics," "attacking," "defense coaching," "goalkeeping." "Mental Coaching" is important for "ball control," "Shooting," "GK handling" and " GK shot stopping" (for training). Virtually all of the stats are important for assistant managers, especially the judging player stats and tactical knowledge. Those have been my observations.
I have only been playing FM12 for about two months, and I have noticed the coaches' stats have been tweaked a bit since the last two versions of the game.
I'm currently curious about the way that the B Teams affect development when managing in La Liga.