Answer to question no. 1: As long your wife and son/daughter already have the qatar visit visa.. there is no need for them to undergo medical in manila. If your family arrived here in doha and you want them to extend there visa (max. 6 months) then they have to undergo medical exam in medical commission.

Answer to Question no.2: As i know only children ages 12 above will undergo medical exam. Only they take your blood sample and x-ray results.