Should all children have their tonsils removed?

Absolutely not. Unless the child has frequent throat infections, a complication such as a tonsillar abcess, or sleep apnea caused by enlarge tonsils, there is no reason to put the child at surgical risk.
Not specificly. The tonsils & adenoids do grow faster than the kids do until the age of 8, with some additive effects due to infection.Some will need tonsils & adenoids removed due to sleep disturbances or chronic infection. In most, the t&a growth stops @ 8 or so but the kid continues to grow & the relative t&a size declines. By adulthood their relative size is similar to that at birth & no problems remain.