On the earlier chrome bumpers, for the front and rear, what all needs to be taken off, to remove the bumpers?

Remove the four bolts with a 13mm head from the wheel wells. A 3/8 drive ratchet with a 6 inch extension works well.

Is that apply to both bumpers, or just the front?

The two front bolts (on each side) are accessed from inside the fender well.

For the rear, the upper bolts (single each side) are accessed from the trunk while the lower bolts (single each side) are accessed from below.

Just crawl under there, take the lower valence off and it’s a snap...if I can do it anyone can

You dont need to remove the valance to remove either bumper

It's a 3 minute job unless the bolts are really rusty.

Locate the 4 bolts for each bumper. Spray some PB Blaster and let them sit. 99% of the time they are rusted, breaking a bolt in the bumper is not a good thing.