Is the 75 battery affected by these battery/charge-gate issues? What about the 100?
All those (AFAIK) have a D/C Charging counter, and will throttle D/C charges once over threshold - but it is only a little bit, and increases progressively thereafter, but not dramatically.
Are there any 100 cars out there that came with free supercharging for life?
Pretty sure the early ones were before it changed from "car lifetime" to "ownership"
Is it important to you? If you have off road parking (and home charging) then as a means of avoiding home charging cost you are going to be sat at Supercharger for a very long time (at best an hour for every 300 miles or so) ... and charging at home off-peak is usually less than 5p a mile, and can be down to around 2p a mile, so £15-ish an hour.
If you are road-tripping a lot then you'd be saving the Supercharger fee - £0.24 per kWh in UK - assuming 3 miles / kWh then 8p per mile and at best, 300 miles per hour, that's £24 an hour.