After 1h 15m hold, I spoke with Tesla insurance this morning. Just updating the info here.
Because I bought the vehicle used from a 3rd party dealer, I cannot get loan/lease gap coverage. Tesla Insurance only offers this gap coverage when you buy the vehicle directly from Tesla.
Glass coverage in Nevada is covered at the comprehensive deductible rate, which for me in the Tesla app the lowest I can go for a deductible is $500.
The SafetyScore sets itself to 90 by default for the first two months of coverage, and then the premium is adjusted up or down in month 3 and beyond based on actual scoring. Obviously, the closer to 100, the better the driver Tesla thinks you are, and the premium may improve.
The mileage level you select is set for the first 6 months of the policy. Upon renewal, vehicle telematics are compared against your policy level, and "the computer" will auto-adjust the premium for successive renewal periods should you have more mileage than stated. There is no way, according to the Agent, to have a human make any adjustments.
I'm signing up shortly, but the policy won't go into effect until tomorrow. The bindings process at midnight the day you want coverage to begin -- like every other policy I've had.