Applicable for Medicaid or not

I am residing in Richmond, Virginia. We are from India on H4 visa (dependents on husband who has H1 visa) which is valid till 2017. My 2.5 years old son has been diagnosed with a genetic syndrome. He is dependent for all his primary needs. He is under Early Intervention services under Henrico county. His primary insurance is Aetna. We would like to get him more therapy sessions once he joins special school. Please help with the following queries :-

(1) Is my son eligible for Medicaid since he is not a US citizen ? Will he be eligible considering his medical condition / income of the family ?
(2) Will he be eligible for Medicaid Waiver services ?
(3) If eligible, how long will it take to enroll him in Medicaid and what will be the premium to be paid ?