To answer your question, the safety glasses you use must be ANSI approved and can only be in certain hues (no darkly shaded glasses). There is no 'maximum' number of people in your pit area, but keep in mind:
- If there are too many people hanging around, it may mean that the folks working on the robot do not have enough room.
- Large numbers of people crowding around your pit area causes traffic backup near your area, and can block the aisles.
- If someone can't get back to your area, you may miss important messages from queuers or other teams.
- If a Safety Judge walks by your pit and it's crowded with people, they may take note of that if you're up for the award.
- Volunteers from the event and FIRST Staff may ask you to thin out the number of folks in your pit area if they deem it hazardous.
For reference, our team has three drivers and four pit crew members, along with one coach and one pit boss. The pit boss and pit crew remain in the pit area at all teams, and the coach and drivers only leave for matches. The rest of our team makes an area in the stands for us to camp out and regards that area as 'home base' instead of taking up space in the pit.
I recommend reading Section 3 of this year's game manual - At The Events. This really details everything you're looking for. In addition, you may want to check out the FIRST Safety Manual at
www.usfirst.org/community/frc/content.aspx?id=470.
Best wishes this season!