Tier-2 General Dependent from Tier-2 ICT

Hi, Currently living in UK on Tier 2 ICT Visa and it expires end of this year. My Wife is on Tier-2 ICT dependent and working in UK. She has got a sponsorship and she is traveling to India next month to apply on Tier 2 General.
I want to get converted to Tier 2 General Dependent. Could you please let me know the below queries?

1. Can I apply Tier-2 General dependent from UK in country itself once my wife comes back?
2. If I apply before April 2016, will I be able to work in UK as per new rule changes for Tier-2 general dependent?
3. Myself and my wife are paying NI charges, still do we need to pay NHS health charges while making the visa application?
4. If I apply for Tier-2 general dependent visa before April 2016, does it affect my current employment on Tier-2 ICT?

Please provide me your advise and suggestions which is best to follow?

Thanks and much appreciated your help.
Sunil

1. Read Switching to PBS dependent route or extending?.
2. Don't believe in rumors.
3. NI has nothing to do with IHS.
4. "April 2016" has no bearing on your question, so irrelevant question.