yes the computer can be removed from the bracket easily when not in use.

The polar has settings for Bike 1 and Bike 2 so yes, you should be OK. I'm thinking of getting a second set of sensors myself for my training bike.

Heart rate moniter and cadence included.

No problem.

Of course!

The contents are listed under the description tab.

I tried to mount a CS cadence sensor to the chainstay, but it was about 10cm out of range for a CS400 unit on the stem and I had to mount on the downtube. I guess probably the same for the speed sensor - I think they recommend 80cm max. The WIND cadence sensor is shown mounted on the chainstay on the film on the polar website, but they may have a better range.

The battery is 2032 I think, same as in most watches. It won't need recharging and can't be recharged. I have two Polar computers and the oldest one, also a CS200, which is maybe three years old got its second battery just before xmas. Polar afters sales service is also very good. No I don't work @ Polar.

you have to input your weight in lbs, and then you get output in mph.

I would not recommend this for swimmning as it is designed solely for cycling, and therefore, would not be water resistant.