A lot of kittens love to play with wires for some reason. My kittens did this, and when i would catch them, i would shoo them away in a strong tone of voice. After awhile they stopped doing it. If it is a big problem you can go to a store and buy tubing, run your wires thru it, then they cant...
I would spend A LOT of time at the shelter with prospective cats. That way you can evaluate their personalities. It might be best to pick a cat that has a personality similar to that of the kitty that passed away, since you know that Siam gets along well with that personality type. I would also...