Tier 1 General Dependent extension

Hello,

I am in a bit complex situation and need advise.

My Current Situation
I came to UK on Tier 1 General visa in August 2010. I have recently (June 2015) got the ILR valid upto December 2024.
My wife and kids got a Tier 1 dependent visa in Dec 2012 and they came in UK in June 2013(6 months later).

As per new rules, they need to spend 5 years in UK for their ILR. In that case I need to extend their visa as a Tier 1 dependent.

I need advice on following
1. Since my dependents got their initial visa if 3 years, most likely they will get extension for 2 more years. This will leave a gap of 6 months (since they arrived in UK, 6 months after getting their first visa). Will that men I will need one more extension for 6 months for them?

2. As per new rules, I need to apply for extension and pay for Health surcharge as well. Can I ask for extension for 3 more years (rather than default 2 years) and pay for 3 years of Healthcare surcharge so that I need not go for one more extension for my dependents?

3. I will be getting my British nationality next year (Aug 2016). In that case will situation change for eligibility of my Kids (age 13 years and 6 years) and my wife for citizenship? Will they still be able to complete 5 years for their citizenship?

Thanks in advance.

1. Since you have ILR, period of grant for leave to remain as PBS dependant will be 3 years (319D(a)(ii)). So there will be no need for an extension.

2. Irrelevant because of above.

3. Nothing changes for them.