My 16-month old son has had seven ear infections since birth - does that he needs tubes?

Likely. My mantra was "5 in a year or one that won't clear" (in 90 days). Back to back infections can produce a middle ear mucus that has the consistency of axle grease.It is almost impossible for such mucous to be penetrated by antibiotics (cure) or to drain if sterile.Part of the tube process involves sucking out all that muck to start over.I'd consult an ENT & expect to see it done.
Possible. Frequency, age, exposure such as day care, response to antibiotics are among many factors that need to be considered. Check with your pediatrician for their opinion on your specific case.
Probably. You should take him to an ear, nose, and throat (ENT) specialist.