It is OK to use eye drops while wearing contact lenses. But you shall use the eye drops that specifically say can be used with contact lenses, just to make sure so as to minimize the risk of the eye drops reacting with the contact. In fact, if you have a little dry eye, you are not recommended to wearing contact lenses, you may try prescription eyeglasses. Or not just always wearing contact lenses, you can wear prescription glasses sometimes.
You most definitely can put eye drops in while wearing contacts, but it depends on the eye drop. Try to get an eye drop specifically for contacts. If the eye drops are the type that gets the redness out of your eyes, then no, you can not use those with contacts. There are drops specifically designed for contact lens wearers suffering from dry eyes but it is very important to talk to your Optometrist before using any drops.
Of course you can. It is good for the moisturizing and lubricating of our eyes and keeps our eyes healthy as well. However, there are still some points you should pay attention to if you want to use regular eye drops while wearing contacts. The first thing is that you must choose some eye drops specially made for contacts using. Secondly, you'd better go to some formal glasses stores or pharmacy to buy these eye drops, so that the quality and safety of the drops can be secured.
Generally no, you couldn't, except the ones made for the contact lenses. The different elements of eye drops could be absorbed and accumulated on the surface of the lenses. The local high concentration of drugs is harmful to the eye tissues. On the other hand, it will change the texture of lenses, hard and turbid. As to those eye drops with colors, it should definitely not be used, because the lenses could very probably be stained by the colored compositions.