Is this memory compatible with a Power Macintosh G3 B&W?

As long as it's the lower density stuff with chips on both sides it should work. Sometimes high density works but I've never had great luck with it in those machines.

Should work just fine - but I wouldn't count on any of the claimed performance benefits for this particular pair of modules making any actual real-world difference - RAM overheating isn't really a problem in the B&W machines, and the CAS latency likewise doesn't really come into play given the speed of the the other components and buses in a B&W.

M