@sagd
Well, if that's not just educational project why don't you use higher resolution ADC? There are 18F series controllers with 12-bit differential ADCs (if you must use 18F series).
As for the compilers you could start with MikroC. It has a lot of libraries that are simple to use, it's well documented and you can find free books on programming in C on their website. At a later stage you could always switch over to professional compilers which allow you more freedom in customizing preexisting libraries and produce leaner and tighter code (very often MikroC libraries are resource hogs).
Just a thought. ;-)