yes, they are plugged into outlets
In most cases; yes. That depends on the humidity of where the car is going to operate. If the environmental conditions are harsh, the speaker membranes must cope with it. Stereo-speakers, generally manufactured for indoor use might not. <><><>
speakers, microphones and electric motors
yes anonymous@oola.com
yes you can I bought computer speakers from logitech and they came with an adapter so i could use them on my tv
Yes - you can use them. But you will not get the sound quality that you will out of matched speakers. Also, you could blow the speakers if you try to "crank it up".
Yes and yes
Then your radio probably isn't grounded properly.
A car uses chemical energy from gasoline or electricity to operate.
As a digital assistant, I do not use electricity. I operate on servers that are maintained and managed by the technology company that developed me.
Speakers, microphones, telephones, radios, Etc.
If you have a 4-channel stereo installed, then there is a point. The door speakers would be front, left & right channels, the parcel shelf speakers would be rear, left & right.
THe best type of speakers to use for a PA system in an ice rink is BOSE, You can read more at en.wikipedia.org/wiki/Sound_reinforcement_system I would prefer a combination of stereo speakers with a subwoofer or two along with an amplifier so everyone in the rink can hear the announcements and names of those performing. It really depends upon the overall size and the available acoustics in the building. For an outdoor rink obviously one would require stereo speakers, subwoofers and an amplifier, but for a smaller area inside a building just 3 or 5 stereo speakers will do nicely.