Going backwards, can't even get a basic blinky working now

[tumbleweed]

Also, if you're using a crystal then probing the OSC1 and OSC2 pins is going to throw things off, and could even make it stop oscillating.
Usually with a 20M xtal you want smaller caps, not larger ones. You might get away with probing the OSC2 pin since that's the output drive...

IMHO you're better off using the LABX1 instead of a breadboard. That ICS502 clock generator will give you a nice logic-level output.
For the 18F4550 I'd set the CONFIG to use external clock mode, not xtal (EC, ECIO or ECPLL)

Also, the 16F877 take a long time to erase and program

The PK4 can take a while to switch chips, and it's not great with some of those really old devices. It's even been known to blow them up from time to time (the VPP generator can overshoot > 20V)