ILR Application for over 18 Dependants

[longhorn1]

Could you please help clarify the following scenario for me:

I am a Tier 1 (General) Migrant with 2 Teenage daughters now aged 19 and 20. They all came in to the UK as my dependants in 2008. They are both in Uni - year 2 and 3 respectively and both still living with me as my dependants.
My initial entry clearance was stamped 12/02/2008 (HSMP); while theirs was stamped 05/03/2008. I arrived the UK in May 03, 2008 while they joined me in August 15, 2008
We did the extension in 2010 and our current Resident Permits will expire in April 06, 2013.
I am going for my ILR in March 2013.

- Can they apply same time with me though separately using SET(O) form?
Will they pay the same fee as me( the main applicant)?