1. Not all features apply to all platforms, best discuss it with either Customer Service, if you haven't purchased it yet, Technical Support if you already have purchased it. Both linked HERE.
2. No. The software doesn't use signatures, rather engine updates. But again support can answer your questions better than I. I do know that "System Restore" will wind back the clock but the software will then immediately update. Support have been known to withdraw an update, that's rather rare though.