You can certainly wear glasses over the top of your contact lenses, that presumably will have a small correction for astigmatism and will improve your vision. You can try extended wear toric lens that will correct your astigmatism, give you better vision and be a better option. They are readily available. Surgery is another story and maybe something you want to consider if you do not get good comfort and vision with contact lenses.
There is no harm to your eyes when you wear computer glasses over your colored lenses. Computer glasses' main value is to prevent the radiation, most of them have no prescription. But I'm doubt whether your colored lenses is also plain. If so, there is no need to wear both of them.
Even though it won't damage your eyes, it'll never cause eyesight dropping either. It can make your eyes easily get tired.
Well, yes, of course, you can wear computer glasses over contacts. First, you need know what computer glasses are. In daily life, computer glasses can be used at a condition when you are watching computer with them. By wearing them, it can reduce headaches, neck strain and eye strain. Anyway, it can be beneficial. And also, it will be fine to have computer glasses with contacts. So you do not need to worry about it. It is noted that there will just take a few days for your eyes to be accustomed to computer glasses