Shortly after you are finished with chemotherapy your hair should start growing again.
It may take a couple of months to start, sometimes sooner. Everyone is different.
Hair grows on average one half inch a month, so your hair could be about six inches long after a year.
Many women stop wearing their wig when they have enough hair for a cute short style. Those who don't feel comfortable with such a short cut wait until the the hair is much longer and can wear a style closer to what the originally had. It's a personal choice.
Your hair may come in different ( curlier, straighter, lighter or darker.) A change in texture and curl is what I've seen most often. This is usually temporary and will most likely revert back to what your hair was like before treatment.
It's not uncommon for someone with very straight hair to have it come in quite curly at first. Again, this is usually temporary.
As for when you can start coloring your hair again, I suggest asking your Doctor. When you do start with color again, stay away from products with harsh chemicals. Look for PPD Free and Ammonia Free. These types of color are safer and gentler. PPD is a known carcinogen and Ammonia is an irritant to skin and the fumes are pretty nasty.
As I said before, everyone is different. This information is base on what I have found to be most common, your experience may be different.
I hope this helps, John