Opinion and rough price on garage renovation

Hi all,
I've been looking around for rough prices on a renovation I want done, prior to getting proper quotes. I found here and am hoping some people can give me some pointers.

I have a house with a built-in single car garage. Having two cars, I'd prefer to widen the driveway, put in a carport, and turn the garage into an office.

The driveway slopes down to the house, and I occassionally get water in the garage.

What I want to do is:
1) Move the hot water service out of the garage, into the laundry at the oposite corner of the house.
2) Build up the flooring by about 4 inches to match the rest of the house (area is roughly 4m x 6m.
3) Brick up the roller door and put in a window
4) put a concrete sleeper across in front of the wall to ensure the car never hits the wall if I misjudge the slope.

Can anyone give me some rough estimates for materials and labour?

Thanks
Scott