DLA and income support top-ups for IB

Hello, I've a few questions I really need answering here.

First of all, I've been on DLA higher rate care since May 2008, and no-one told me that I could claim Income Support on top of my IB, which went to long-term rate in September 2008, and again no-one told me that even that qualifies me for the Income Support top-ups, either way including extra premiums for disability.

Does anyone know whether I will still qualify for these Income support top-ups under the new rule changes? I'm hoping that I might just beat any deadline. I've asked JObcentre people for an IS application form just in case.

I went on the Direct.gov benefit checker/adviser and it seemed to say I might be entitled to £30.75 of Income Support. Is this just a flat rate of extra benefit, or is it one of the premiums for disability?

Also, I know that higher rate care DLA means it can get you 'disability premium' of around £28, and any rate of DLA can get you 'enhanced disability premium' of around £13. Do these extras overlap, or can you get them added together?

Just wondered if anyone knows of any other disability premiums, apart form severe disability premium - not entitled, as I live with family.

And does anyone know whether there is any way I could get any of the income support backdated to when I was first entitled in 2008?

Any help gratefully received.