External speakers for a Sumsung 42" plasma TV
Welcome to the forum.
1. I can answer the questions, but to know if you have the required connectors on your television, I'm going to request that you post your model number so I can see the jack-pack (sets of connectors) you have on your television.
If you'd like to add speakers, you can do that a couple of ways: the most common would be to use the audio out RCA connectors and then mute the television speakers. This DOES mean that you won't be able to control the volume with the remote. You will need an amplifier of some sort - although, a small boom box with an auxilary input will do the trick, as will a receiver.
If you have a headphone jack on the side or back of your television (3.5mm headphone jack), you can connect that to a boom-box or powered stereo system. With that, you can control the volume with the remote control. Some people use powered computer speaker systems (stereo or 2.1 with the .1 being the subwooofer) and the headphone jack with satisfactory results.
Non-powered computers speakers will not work from the RCA jack in the back, and may work sluggishly with the headphone jack. I really recommend using a powered speaker set.
Let me know if I can clarify any of the above or assist further.