Is it normal for kids with ADHD to be shy?

It can be. Some children with adhd also have trouble with social cues. They don't always pick up on either the friendly encouragements or the "you're in my personal space" signs from others. They may feel that other kids don't like them. They can learn how to read social cues, though, through role-playing and socialization therapy.
Yes, Depends. If a kid has inattentive type adhd, then shyness would be a more common personality trait. However, if a kid has hyperactive type or combined adhd then the behaviour tends to be more outgoing often excessively. Impulse control with procrastination always seem to be common traits as well.
Yes. In children and adults with adhd, some of the most common co-occurring disorders are anxiety disorders. The reasons for that are many, including genetics and a tendency for some people with adhd to be shy because of how they feel bad about the effect of their illness on their friendships and school/work.
Yes. They have trouble keeping track of information about people - starting with their names - and live in fear of embarrassment at mixing that up. Some deal with it by becoming clowns, and turn these mistakes into pratfalls and jokes.
It depends on the. Type & presence of learning disabilities. Shyness is a personsality trait often noted in kids who had a " slow-to-warm-up " temperament in infancy & in some kids who recognize (amazingly early on) that they're not able to converse, behave or perform academically at the level of their peers. A few parents still come in saying, "i don't want him/her to know he/she has a problem." 'nuff said.
Yes. They may be shy in circumstances you would have guessed they would not be, and overly gregarious, friendly, when you would have guessed they would not be. Often they have more problems with peers nearly the same age but not with kids 2+ years younger than they are, and they may relate to strangers better than to people they know well.
In a way. Adhd kids are often in trouble and have low self esteems. They may be awkward as they are over active much of the time. So, these factors may associate with shyness.
Not specifically. Adhd is also associated with impulsive behavior which can relate to being a class clown. There can be comorbid behaviors such as OCD or anxiety disorders, not specifically related to adhd, that can interfere with socialization.
Not Necessarily. Kids with adhd do not consistently present as being shy. However, they are often awkward in social situations, and this is the most common reason for their interpersonal difficulties.