Is it bad to do squats everyday?!

This is largely dependent upon one factor, the intensity in which you train.

If you are trying to gain muscle, you want to lift fairly heavy. This sort of training requires adequate rest. the heavier you train and the more you push yourself, the more time needed for rest.

If you are doing general conditioning and maintenance, then the weight used will be much less. This sort of training requires very little rest and can be done daily. Though you should always give yourself either a day or two of rest a week.

A good indicator of intensity is as follows.

If you can complete 12-15 reps without much issue, this is a lower intensity.
If you are struggling to complete the 12th rep, this is moderate.
If you are having trouble completing the 8th rep, this is a heavy lift.

In higher intensity, you will always reach muscle failure (or come close).
In lower intensity, you should never reach muscle failure.

Yes. It's important to rest your muscles. And it's been proven that if you mix up your workouts and keep the body guessing, you will lose more fat and gain more muscle. I recommend making a workout plan for each day.

Not necessarily...depends on how many you do. They will keep your legs in excellent shape, but if you're really doing them every day, you shouldn't have to do very many.

Yes. How can you ever get stronger if you don't allow your muscles to rest? It's important, look it up.