there are materials inside of the crystal to help them grow
Crystal's grow by a process called nucleation.
Yes, you can steam acrylic yarn to help remove wrinkles and shape it.
Well, unless you're a crystallographer or geologist, they don't really do much for you at all.If you're one of those, then the crystal shape can either help you understand how the crystals grow (for the former) or help you identify the mineral (for the latter).
yes
NO
A small quartz crystal can grow about 1mm a week assuming it is in a stable matrix.
a nucleus or plural nuclei
A crystal
how cold?
no
Yes, you can steam block acrylic yarn to help shape and finish your project.