Most commercial skeins today are made to be pulled from the center, and they don't need unwinding. If you want to roll the yarn into balls, the old fashioned way is the only way I know of, simply start at the end and lift up on the yarn. Roll it up as it comes off the skein, and then pull more off. It is a very time consuming process. You have to use some care to prevent the yarn from getting too twisted. I usually just let the skein bounce around loose on my lap, or on a clean cloth on the table.
VERY carefully. I've only seen hanks made out of natural yarns and that means that the probability of making a tangle mess if you are not careful are astronomical. Hanks have two twists, one to make it compact, so if you tug it, will give in and you'll see it's a huge circle twisted within itself. Now you'll see that there are ties all around the hank holding this huge circle together. All except one, are pieces of surplus yarn tying the circle together. Here is where it gets interesting, you should have another person with his or her hands inside the circle of the hank making the circle taut. Cut the ties that hold the circle together and start winding the yarn into a ball or to a machine if you have a yarn winder. By any means DO NOT knit right out of the hank, the friction will lock the yarn together and will create a HUGE mess. I learned my lesson with raw alpaca yarn I got from Argentina. I cried my eyes out and had a troupe of knitting buddies unravelling the hot mess I created.
SOAK it in warm water with a little bit of detergent with VERY LIMITED agitation to avoid the wool felting. Rinse in clean, cool water and hang to air dry. If the spun wool is "kinky" or curls up upon itself, hang something off the end of the skein to weigh it down a bit. (I use a spray bottle filled with some water for it's handle is a built in "hook" that hangs off the skein easily.)
A skein of wool can come in different weights. There is not a specific amount of wool needed in a skein.
The weight of a skein of wool can vary depending on the type and brand. Typically, a skein of wool can weigh between 50 to 200 grams. It's best to check the label on the skein for the exact weight.
Skein is a non-standard length of spun fibre, which can be wool or any other fibre.
A bale of wool. Or a skein of wool.
Skein
Yes, you change wool -- unless you find avariegated wool skein or set of them, that offer you the colours that you want.
A bale of wool
hank
Collective nouns for wool are a bale of wool or a skein of wool.
A group of wool is typically referred to as a skein or a ball of wool, depending on its form. A skein is a length of yarn wound in a loose loop, while a ball is yarn wound into a round shape.
The term 240 gr indicates the total weight of the skein of wool.
A small amount of wool yarn is typically referred to as a hank rather than a skein. A hank is a looped bundle of yarn that needs to be wound into a ball before use. A skein is a different form of yarn packaging and usually contains a larger quantity of yarn.