Do blind people know what colors look like?
Some do and some don't. It depends on how much the person can see if anything at all, and when they went blind. Some blind people can see colors just fine and others can see colors but have a hard time telling them apart. People who were born totally blind or only with the ability to see light/dark or shadows won't know what colors look like. Someone who went blind a long time ago may or may not remember what colors look like. If you're wondering about a specific person, just ask them.
Can deaf people enjoy music?
Some can and some can't. It depends on the level of hearing loss and the individual. Even profoundly deaf people can feel the vibrations from really loud music. People with less severe hearing loss can usually enjoy music with hearing aids or special amplification devices, though some may not be able to enjoy it cause of the compromised quality of the music. It depends largely on the individual and how their brain makes sense of the music coming in. Memory can be helpful for late-deafened individuals, and their mind can sometimes fill in the gaps to songs they enjoyed while they were hearing.
Are deaf, blind, and deafblind people's other senses heightened?
Yes, deaf, blind and deafblind people have heightened other senses, but not in the way that is commonly thought. The average blind person scores the same on a hearing test as a sighted person and the average deaf person scores the same on a vision test as a hearing person. The difference is that sighted and hearing people who have information coming through five senses filter out a lot of information. In other words, the brain lets pass through any important information and throws out any useless information. In someone who is relying on four or three senses, their brain filters out less of their remaining senses, making it so that they are receiving more information from each sense.
The average deaf/blind person is more aware of information coming through their sense of touch and smell than the average hearing/sighted person. Deaf people compensate for hearing loss with their vision and blind people compensate for vision loss with their hearing. However it's also important to keep in mind that every individual is different. Some people are more sensitive than others and the same person is more alert at certain times of the day than other times.