PowerMac G3 Blue & White motherboard questions

I have a late-model PowerMac G3 Blue & White (Apple's codename for it was Yosemite) and I noticed some things on the mobo that I'm curious about. Here's a few pics. I'm wondering if the unpopulated headers for a 3-pin fan connector and the DVD sound cord could perhaps be soldered in and then used. Would that work or am I just pipe-dreaming? Also on the second pic, what does ESP/ICT stand for on that unpopulated header with two rows of 8 holes each? What would that header have been used for if it were populated?

The DVD audio cable is likely useless or is a duplicate of the CD audio cable. Only 68K Mac apps used the audio cable.

The 8 pin header is likely a diagnostics port.

The fan headers might work but you'll need to test them with a DMM.

hmm...thanks for the info. What about the X-shaped header with 5 holes for pins, labeled "USB Port 0" (just to the left of the 3-wire plug with red green and black wires)?