I think the parasitic drain on the 3 lights mentioned (with switch leds turned off) are a bit higher than the self discharging rate of the battery. It would still take years to fully discharge.
Not too many. Some people just like certain things.
Certain drivers have ultra low electronic switch parasitic drain. Only a few though. If one is planning to use a different driver then things change, parasitic drains can become quite large.
I asked because I may be changing the driver in my GT mini and it may be preferable due to the UI for me to use a mechanical switch. The SS ring around the rubber boot is press fit in the GT mini, not recommended to remove it and I’m sure it wouldn’t be easy to do, might even be loose upon trying to reassemble. Still though, it may be possible to approach the situation from another angle….