Making up prayers which were intentionally missed

When I was a reckless young man, during the period of my youth, I abandoned the prayer (salaah) for a period of six months; [thereafter] Allaah bestowed upon me guidance and uprightness, and [the conviction to] preserve the [daily] prayers at their [appointed] times. [Now] should I make up the prayers which I had abandoned early on in my life? And are prayers [ever] required to be made up?

The most worthy of leading the prayer

Who is the most worthy of leading the [congregational] prayer; is it the young child who has not yet reached puberty – but has memorised half of the Qur.aan, or a man who has only memorised 5 chapters [of the Qur.aan], as well as being upon the Sunnah, and [of sound] ‘aqeedah, and possessing knowledge of hadeeth and fiqh; and may Allaah reward you?