1. Dental: they are not concerned about the chemical reactions, they are more concerned that loose dental might break/fall/slip off while you are sleeping and cause a problem. You were on your back through it all. Further Loose teeth may be indicative of a low grade infection issue which could easily become a huge post-op infection.
2. Make-up: They are not so worried about makeup getting in the way of the operation, they are worried by the simple fact that most women do not buy new makeup as often as they should or know about using sterile tools (sponges, brushes, etc) to apply make up. Your make-up kit can be full of bacteria which are just dying for an opportunity to become a problem in a sterile operating room. Deodorant is questionable, do you use stick or spray? I know that they suggested I shave (my face) the night before and wash my face afterwards (to reduce the number of critters carried on my person).
Further there is a change that they might have to say put a tube down your throat due to a bad reaction to the anesthesia, in that case a face full of make up would become a problem. Eye makeup is a concern because sometimes they have to tape your eyes closed (They do mine because I flat refuse to close my eyes when under).
3. Bladder. The anesthesia actually paralyzes your body it doesn't just make you sleep deep, it actually prevents you from moving while under the knife. Making certain you can urinate is just making certain that you are no longer under the paralyzing influence of the anesthesia.
It takes a long while to fully flush out the anesthesia out of your system. Some people fall into a real sleep in the post op area - some wake up nearly immediately after having oxygen put on them (I tend to wake up on the way from OR to post-op - annoying the attending nurse

). Just waking up is only a step in the recovery process, be able to cogitate, motivate and balance comes a little later, urination (feeling like you have to go) is a sign that your internal sensors are functioning, actually going means your body is flushing its system like it is supposed to.