That is normal. The average person wants to have fun, vacation, and/or spend time with the family on holidays and weekends instead of surfing on the web.
Yes it's common for your site traffic to go down on the weekends. Most people using the internet have lives and are away from their computers but not us
My traffic usually goes down on holidays and weekends except for when I did a holiday special on my link directory...
Very normal (for the major ones) since people are busy with family etc. But not too much since others don't have school/work so they have time to surf while they're not doing activities.
It depends on your niche, but in general yes. Most of my sites are education related, meaning that they get the heaviest traffic during the school week while on weekends the traffic drops off considerably. Holidays and other major events also cause a major dip in traffic simply because people are out of the house or doing things other than using their computer. Again, it is obviously dependent on what your site's topic is. Turkey recipe sites would go through the roof around Thanksgiving and Christmas while patriotic music sites would be even more popular around the 4th of July.