Our company has 100,000s+ photos, how to store and browse/find these efficiently?

1: yes, Explorer does not like 10.000 items in a directory. 1000 is b etter. This is NOT a file system issue - you can dsafely store 100.000 files in a folder and work with them efficiently from the command line. It is Explorer being slow.

2: Velociraptor 600gb disc. 10.000 RPM. Fast. Need more then get the money for SAS. Or wait till things get cheaper. If i need a truck, I need to pay for it.

You need to look at digital asset management software. DAM software is built to manage large collections of photos/videos/audio. They are usually backed with database to manage media catalogs. One example is MS iView