As far as the "Tracks per CD" debate goes, I personally prefer about 8; that way I don't spend too long searching the CD for the track I want once it's in the CDJ, but likewise I don't spend ages searching through my CD wallet in the same way you might if you had only 1 or 2 per disc. It's a nice balance and it works for me. Also gives me room to properly get down all the info I want on each track (name, key, length of intro/1st drop/breakdown) on the little piece of paper that accompanies each CD.
Another thing to think about when debating between buying cheap vs buying expensive for your first set of gear...something that I've found with learning to mix as well as most of the instruments I've learned to play to a good standard, is that if you start out learning on an absolute shitter, and you can get to a reasonable standard on that, then when you actually get round to playing on or buying a better quality, more expensive one, you'll sound loads better almost overnight. Case in point: I started learning guitar when I was about 8 on a shitty Tesco electric and painstakingly put the hours into learning chords, scales, licks, etc. for about 3 years before I got the chance to play on a Gibson SG - and everything was so much easier, faster, cleaner, better sounding because of it. I guess it's like if you learn to drive well in a shitty old car with no power steering, rubbish handling and awful brakes, and then get behind the wheel of a brand new BMW 5 series, you'll feel like such a better driver already. Even if it is just a placebo effect, it works for me!