help with simple project

[erikh98]

Hello. I'm hoping to get some advice on a simple project.

Basically, I need to move a straight arm from an initial (vertical) position, through 90 degrees to a (horizontal) position, to be activated by a switch and a 12v dc power source. The arm will pivot or rotate at the bottom:

initial position: |

ending position: __

the arm needs to reverse or toggle between the two positions with each activation of the switch as follows:

initial arm position: vertical
on switch:arm horizontal
on switch:arm vertical
etc.

The arm will have no more than five pounds of weight attached to the end opposite the motor/pivot point.

Questions:

What type of motor should be used?
How do I determine the required torque rating of the motor?
Any external control electronics necessary?
How to vary the speed of the motor (vary speed of arm movement)?
Any other considerations?

It's that simple, but I'm a complete newbie, so any help is appreciated.

Erik H.