Regarding the choice of ARM Cortex... I only identified that particular chip (LPCx), because it just happens to come in a DIP package, which is useful for prototyping. I don't think it's the right chip for the long term, because there are better chips out there (e.g., some of the Atmel chips I referenced), but the better chips don't come in DIP form. I agree that h/w multiply/divide would be very useful. However, for a simple test of grabbing camera data, and not doing any major manipulating of the image (e.g., JPEG decompression), the DIP CPU would probably work, I think.
Personally, if someone is comfortable creating a prototype board using surface-mount (BGA) chips, then I say to skip the LPCx altogether, and go for a more serious chip. And forget the 128KB to 512KB SRAM. Go for as many MB as is cost-effective! But that's just my opinion.