For each set, you can only redeem the Prerelease code once for most sets, and up to 5 times for MKM, OTJ, and MH3
Pinnacle Starcage will be vital to the Azorius Control archetype for the same reason Temporary Lockdown was - it helps stop early aggression
I fall closer to the second camp, but I think anyone can see that the list makes sense within the context of the format
All of the original Moxen are powerful, but Sapphire is the king
Because they cant do anything at all with that mana during your turn, it guarantees that all of your opponents will be losing 3 life each turn and you still get extra mana out of Yurlok
However, if you have the right board presence, you can pitch two red cards from your hand to cast Fury of the Horde