Ejection Seats and Operating Envelopes
Woff.
The short answer is yes. To both. The upper limit is for the obvious reason. The lower limit is to avoid injury to slightly built people.
Some people have had waivers granted. Heavy guys have been known to have a zero/70 limit instead of zero/zero. Meaning they need 70 knots before they can safely eject. A standing start might not give their parachute time to inflate correctly.
BV