Solid surface is man made. Granite is natural stone.
Solidsurface discolors easier comparedto granite....but what kinda difference are you keen to know?

Solidsurface quoted to me was about RM180per foot run, whereas my research on stone suppliers along JlnIpoh is about RM43per sq foot.

There's a whole lot more you can derive by googling granite vs solidsurface

Yes , the measurements are customizable. There is a maximum length though. What ever it is, they'll be able to join the granite together to form a 10 feet by 3feet table top.

It is RM43 per sq feet, at least for the ones I'm interested in. Not sure if the color you like is rare and more expensive. Do check out the shops along Jalan Ipoh. Searching for counter top on your own is surely cheaper than engaging an ID or kitchen planner's fees. However its highly recommended to go with a suplier recommended by the designer.