Headlight Covers

So I just ordered a pair of headlight covers (smoke) from PFYC and I have 2 questions.
1. It says they just snap on.. so would I have to be worried about people stealing them? I'm still in highschool and I drive to school (where there's a lot of [immature] people) and I was wondering if I should leave them off when I go to school.
2. Would I have to take them off at night? From what I've seen, Grand Prix headlights definately aren't the strongest headlights out so would the tint be too much for the lights to get out good enough to where I wouldn't get pulled over? "Get brighter headlights" - I know I would of heard that in here and yes I'm planning on it but I have other things to do to the car first.
Thanks in advance.

Yes they are easy to steal, and yes, you'll need to take them off at night to be legal

Another thing, if I got the 6000K headlight bulbs, would I still have to take the covers off at night?

yes, you'll still need to remove them. brighter or higher wattage capsules will just run hotter and possibly damage the reflector, clear lens, and/or wiring.