There is a limit rule.
Click on the 'nfhs.org' link on this page to go to the National Federation of State High Schools Association's football page.
Maybe the rule that keeps the clock running if the score get to high at a given point in the game. i.e. 60 to 0
No. This rule only exists in the NFL.
I believe college and High school have the same rule on this matter. Any eye shield worn, a dr's. note must be shown to the game officials. Not sure about tinted shields, if there is an existing eye condition do to brightness of sun or lights I'm sure a Dr'. note would work. <edit> There cant be any tint to your shield if playing in high school. All must be clear
It is illegal to wear them in high school for safety reasons.
Rule High School - Knoxville - was created in 1927.
Rule High School - Knoxville - ended in 1991.
CA uses the National Federation rule book as do all states except Massachusetts and Texas.
For every lighting strike you have to wait 30 minutes this is for a game though not sure about practice.
High school and NCAA yes they can go downfield immediately. Only the NFL has a rule where ineligibles must wait for the ball to be kicked.
The cleat rules for high school football take up 5 paragraphs in the federation rule book. Basically cleats cannot be longer than 1/2 inch and if metal tipped the metal must meet minimum hardness standards.