It has already been announced that Tier 1 Visa extensions are to end by April 2015, and options for Tier 1 General Visa holders to settle by April 2018.
See,
http://www.immigrationboards.com/uk-tie ... 45715.html
So if you were to extend your visa in April 2015, which will give you additional 3 years, you will still need 2 years to be eligible for ILR in the Tier 1 General category. Alternatives are you come in, get your additional 3 years, and then switch into another eligible category (not going to be straightforward) to be able to settle later on.
Applying for your dependents to move with you should be no hassle, as long as you satisfy the maintenance fund requirement to be able to support your 2 dependents.