no
Nah, they're man-made material designed not to shrink.
The polyester will shrink.
millions of it
If the soccer jersey is made out of polyester it is not going to shrink. If the jersey is made out of cotton washing in hot water will shrink it.
"The simplest way to shrink polyester fabrics would be to heat them to about 80-90C." Excerpt from a science article linked below. It gives you the how-to and how and why it shrinks. Article from 1999 http://www.madsci.org/posts/archives/nov99/943908244.Eg.r.html
Anything with cotton in it will shrink some if it has not been preshrunk. The amount it will shrink depends on the percentage of cotton in the material. The more polyester the material has the less it will shrink.
Yes, it will shrink.
No it doesn't. The way to test if a garment creases easily is to scrunch up a section (in your hand) before you make a purchase. If the material is very creased when you release it, then it will look the same way after you have put it on and sat down in it. Linen is terrible for doing this.
No, they have been pre shrunk.
Yes it does it even stretches when not in the dryer
No. Acrylic and cotton blend should not shrink.
Probably the most important way that polyester is better than cotton is that it does not shrink in the drier, unlike cotton; however, cotton is generally softer than polyester.