1) If you have to ask this question, then I respectfully suggest that you're treading in an area that can get you into trouble.
2) A "legacy" software key is a computer file that, if present on your computer and "loaded" into CPS, allows you to create and modify all settings for the particular trunked system for which the key is made. An ASK is a hardware dongle that is provided by the trunked system administrator to folks intended to be authorized to create and modify only certain settings on that system, and (optionally) which also locks the radio from being programmed or modified by anyone lacking that ASK.
