My favourite 8 pin is the PIC12F683.. it has the PWM module built-in and can run up to 8MHz internal OSC... really nice device.. ADCs, comparator as well.

Forget the 10+ years obsoleted PIC16F84A device , use his big brother 16F628A (even if almost obsolete as well) or 16F88, PIC18F1320.. oh well so much in the list I keep 50 different model for 10f to 18F, 'round 20 for DsPIC and PIC32.

I suggest you to have on hand both 16F88 and 18F1320.

PWM.. not as this critical.. unless you REALLY need it accurate, the internal OSC worked for me pretty well in the past.. and still. My PICMultiCalc could be handy, just go on my website to download it.

RC osc. it's an oscillator built with Resistor and Capacitor. Knowing their temperature variation, you may use it or not. It always depend where and how you will use it. As i said, some, see most, newer device says to be 1% accurate... erm... look the whole datasheet and make your own conclusion. To me accuracy=crystal... but as i said... many application will run anyways with the internal OSC.

Just post your part# and we will have a look at.