The KXPACBL is a set of 4 different cables designed to provide fully integrated operation of the KXPA100 with either the KX3 and KX2 (with KX2ACBL).
A: In order to reduce the cabinet size of the KX2 by 50% of the size of the KX3, we had to reduce the number of connectors on the left side of the KX2. To do this, the signals found in the KX3's ACC1 and ACC2 port were consolidated into the single ACC port. Therefore, to be able to use the KXPA100 and its standard cable set (the KXPACBL), the KX2ACBL cable was made so that you can have complete integration of the KX2 and the KXPA100.
A: Yes, that's correct. In fact, full integration means that you do not have to manually turn on the KXPA100. It will power itself up automatically when you turn on the KX2. After that, you'll be able to select up to 100 watts right from the front of the KX2, too.
Further, if you've got the KXPA100's internal tuner, the KXAT100, you can select one of 2 ANT ports and the autotuner itself will be controlled from the KX2.