Is it weird for my son to have ADHD inattentive type instead of the hyperactive type?

Not at all. The predominantly inattentive subtype of adhd is the most common variety in males & females, therefore, it is likely to be present in any child with a higher likelihood. In the "old days, " hyperactivity was used as the predominant symptom of adhd, but we now know that it is the control of activity, rather than the activity itself that is the basic pathophysiology (that which is abnormal) in adhd.
No. Patients with adhd may present with a predominance of hyperactive symptoms; others with inattentiveness and the remainder with a combination of symptoms. The expression of adhd symptoms also may vary as your child matures.
Not weird. I'm not sure that the inattentive subtype of adhd is more common than the so-called combined type (both inattention and hyperactivity/impulsivity), but it may be in the teen years. It is more subtle but can be quite disabling because of problems with missed information, poor organization, and impaired planning and follow-through. Treatment is not as well studied as adhd-c.