Transistor Affecting Timings?

[Gusse]

I've thought about using the clock output of one PIC to be the input on other PICs but it never seems to work for me. Are saying I can dispense with the 20Mzh external resonator/oscillator, remove the define and just connect GP4 to CLKIN on the other PIC?

What is your realistic accuracy requirement and where does it come from?

If LED blinking was just a trial circuit for your end application, then OK. But if your application will be LED blinking device, then I don't get why internal 4MHz OSC with +-1% tolearance would not be enough. +/-1% means max. 5ns/cycle deviation between two corner oscillators (every 50s, 1s time difference). OK, it is quite much, but everything is relative...

20MHz +/-50ppm means +/-1kHz deviation => an error of 26 minutes per year. Is this OK?
With VCTCXO you can have less than +/-1ppm stability.

If you want to use GP4 as an output, then you need to use internal 4MHz OSC, GP4 is multiplexed to OSC2 so XTAL cannot be used.
With external clock source you can use PIC in EC mode.