Gday Ghoot
If you want to compare chips / functions, then the microchip site has a nice parametric search engine
http://www.microchip.com/stellent/id...PAGE&nodeId=74
From here you can search by various means, very usefull.

As to the 16F88, its almost pin compatible with the 16F84 but has multiple ADCs and PWM and and and... Very nice chip.
You could use ADC for yr light sensor, and via a simple voltage divider you can calibrate yr battery warning as well.
Only one warning, the 16F88 uses different registers for controlling the ADC. Ie it uses ANSEL/ADCON0 and ADCON1. Its simple but different to prev chips. As such ADCIN wont work in PBP and you will need to do the ADC manually. Very easy though, and MEL supply some example files to cover this.
You will also need the 16F88 library patches, as the 88 is not in the std PBP.
Andrew