Is the HP EliteBook 8 good for gaming?

No. It relies on integrated Radeon graphics, so modern games run at low settings at best. It is built for office, development and data work.

Can I upgrade the RAM or storage later?

With 64 GB and a 2 TB SSD already fitted, there is little reason to. Check HP's service manual for your exact model before assuming either is user-replaceable.

Is 64 GB of RAM overkill?

For web browsing and Office, yes. It pays off with virtual machines, large data sets, containers or many heavy apps open at once.

Does it have a numpad?

No. The 14-inch chassis uses a keyboard without a numeric keypad, so heavy number entry is slower than on a 15-inch model.

What is the Ryzen 7 Pro advantage over a standard Ryzen 7?

Pro chips add business manageability and security features that IT departments use for remote management. Raw performance is close to the consumer version.

Is the screen good enough for photo editing?

The 1920x1080 panel is fine for documents and general work. For color-critical editing, check the panel's rated color coverage, since business FHD screens vary.