The picture does not give you an idea of the size. Think big for all the ES line of speakers as the center is no exception with two 5 1/2" woofers and 2 tweeters meaning it's big. The dimensions are depth=10", height=7" and width = 18 3/4" and weighs in at 17 lbs. it also has a bass reflex port so if it's in a shelf, make sure it's vibration proof!
Depends on how you measure it. The actual speaker thickness at the back is about 5 inches, but it sits on feet that are a little over an inch high so if you count the feet I would say it is about 6 1/8 inches high.
All you need is 16 gauge ordinary speaker wire.You do not need to buy expensive Monsters cable. Just be sure to connect each end to like post (red to red, black to black) from speaker to receiver using bananna plugs.
The only criticism I have of this speaker is that it's dispersion is quite narrow. It's fine for a relatively small room. You must sit close to center to get the best sound. Good luck.
Yes, my amp only has 110 watts and I never really crank it up so I doubt I put more than 10 watts into it. Keep in mind a center speaker is normally used for the voices, so it seems unlikely you will be cranking it up much. A CD only sends a signal to the two or four speakers, not the center speaker.