Not everyone. 3D TV has two types: one is glasses 3D TV, and the other is Auto Stereoscopic Displays, which you do not need to wear glasses while watching. The Auto Stereoscopic Displays extremely expensive and, in most cases, you have to stand right in the center spot, so they are not good for group viewing, But on the whole the Auto Stereoscopic Displays are the development trend.
Yes, every one watching 3D content on a 3D TV need to wear glasses to see the 3D effect. If you do not wear 3D glasses, the 3D image on the screen will appear distorted. Don't worry about the size of it, most 3D glasses are designed to be large enough to fit comfortably with an existing pair of glasses.
Yep, it is necessary for everyone to do that. Every person watches 3D TV have to wear compatible 3D glasses, thus they can see the content clear as well as effect of 3D. Because the 3D screen is not similar to the normal screen, which would make you have blurry or double vision if you just watch it without specialized 3D glasses. And some 3D glasses are using polarized glasses, which mean each eye sees a slightly different vision of the screen, and the two images deliver to the brain and the illusion of a three dimensional image would be presented.