Dumb gauge question

When I bought my bike, It didn't come with gauges. I will be replacing these with something simple and cheap, now the front wheel has a cable coming from it. I'm assuming that is for the speedo correct?

But my real question is where do I get RPMs from? I have a couple wires coming from the crankcase, one on top and one below, so my assumption is one of these is the RPM sensor correct? And which one? If its not, where or how do I read my RPMs?

Another weird question I have is on the right side just above the foot peg there is a small empty black box. I was wondering what Yamaha's intended use for that box was?

Sorry if this has been covered, I don't know what terms to use to search for these strange questions and I tried. Thank you in advance!

The tach is cable driven from a gear mounted to the oil pump. The outlet is on the right front about 2 o'clock from the oil pump strainer.
The empty box held a security chain that was about the same size of a dogs choke chain.

Ok so I was right about the speedo?
And I found a video using a different bike, but its the same spot.

And ok I will check tomorrow when the sun is up for that cable spot.
Video of the cable.

And security chain? To secure what?
http://www.650motorcycles.com/83lock.html Here's that security chain chain. Interesting stuff lol

Cool now I have all the answers I needed for these things. I am nearly done! Yay!

There are no dumbass questions. Everyone here is learning and I would say that just about everyone likes to help out new people.

If you need new speedo and tach cables, they are readily available and are not expensive.

I disagree with MaxPete, give me time and I will definitely come up with a dumb question.