Have a look at the specific article first, it may answer some of the questions.
You can't get votes as a witness if you're a regular account. In order to signal that you're eligible as a witness, you have to broadcast a specific transaction on the blockchain, which basically says: "hey, I set up my client and I'm ready to produce blocks". From that moment on you can receive witness votes.
Makes sense. Usually a logical answer if machines are involved.....humans, not so much. I have a bunch of machines, 2 of them powerful. I feel they should be raking in some cryptos, somehow....
go for it :)
What's necessary to set up a client? I'd like to look into this in the future.