House Electrical Guru`s...a question or two, ok three

[SuperFudge]

Hello all,
(ill apologize now to the moderators, if this is in the wrong spot)

I am almost completed my fishroom, and have been installing external electrical to feed this room.

I have a basic understanding of the household electrical, but i have a few questions that seem to have me stalled....

I wish to run a line out of my breaker panel,.. where i am wanting to draw this power from there exists an empty double pole breaker. (2x 15 amp)
There is a pin connecting the two switches, so they only turn on or off together.

My question is, if i run a single line (15 amp) out of there, using only one side of the breaker, does this have any effect on how that breaker pops if there is a problem ?.

What would you change or is it ok that way?

Heres #2,

I have an existing armoured cable line running through the fish room, this line was exposed in the garage before the fishroom was built.

This line has 3 wires (14-3?), it is also connected to a double pole breaker (2x15) also with a connecting pin.

There are two Hot wires it appears, red and black each into its own side of the double pole.....with the white going to the nuetral bus.

Does this mean this line is 220?

What is making this confusing for me, is the only things this line is feeding is two unused outlets on another wall...wich are 110...??

Any thoughts on that are welcome and appreciated.

Heres #3,

There is another (pre-existing, but unused right now) cable that i intend to use for all my lighting.
This line has 4 wires, and in the breaker box it appears the green is a ground, white again to the bus.
The hots(red,black) are going to individual single pole 15 amp breakers.

Is this intended for two individual lines, just being in one cable?

Any thoughts would be welcome on the subject..as well on anyone who may be for hire to Pm me if interested in a small side job.


Thank you, Marc.