1. I didn’t see a time limit (or a time track for that matter). Does the battle just go on until one side wins, or was there a time limit?
There is no time limit.
2A. When multiple units attack, and you have one with the same CC as the defender, and two with lower CCs, is the modifier -1 for the one and another -1 for the other two?
You receive -1 for each Participating unit with the same CC as the Primary, and -1 for every two Participating units with lower CCs (rounding up). So, three Participating units for one Primary - one with the same CC as the Primary and two with lower CCs - give you a -2. The defender's CC never matters or factors into any of this.
2B. Same as above except only one lower CC unit. Is there still a -1 for the lower CC unit, or is it lost?
You get the -1; per 7.4, you round up.
3. A unit with a B CC loses a step. On its reverse, it is still a B. Does the unit receive any modifier for having lost a step? (It seems they still function the same, just more fragile.)
There is no such modifier, no.