Tier 4 switching to tier 2

I am on tier 4 visa as a PhD student. I came in England, back in 1st Oct 2010. Last month, I have received my Cos form a trusted A rated University. I am plan to switch along with my 2 dependents. Now I have few confusion to sort before application.

1. For the maintenance issues - the last line of the Cos said ‘y’ and there is no note from sponsor. So does it mean I will able to apply for my dependents as well? ( I asked the HR and they said they note sure about it, it is may be only for the migrant not for the family.)

2. We have visa until Feb 2020, so I can apply for myself and will apply for dependents later with the maintenance of 90 days maturity. My wife came in this country 9 years back, as a dependent she supposed to switch with me. Do you think, to not changing with main applicant her ILR application will affect ?

3. I need less than 9 months for my ILR, can I apply less then 3 years to avoid the NHS fees?

Your answer will be appropriated.

Thanks