"Hard" magnetic core = alnico
"soft" core = iron/steel in addition to some sort of magnet. As you say, the CC has got two large steel  (forged iron) bars.
Regarding eddy currents and other related topics, read this:  http://www.billlawrence.c...upology/Introduction.htm
Yes, L-6xx are sidewinders.
Counting number of windings are - quite frankly - pointless and DC readings tell nothing about tone. The original CC, which is the model vintage guitar buffs drool over, had AWG 38 wire by the way
The higher the AWG number, the thinner the wire, so AWG 38 is very heavy by today's standards. AFAIK, the most delicate wire Bill uses is AWG 46.