As far as Mac's go, You don't want to take the battery out. The laptop will actually reduce the processing power available when the battery is out. I am not sure of the particulars (whether it reduces the amount of available cores or if it reduces the available processor speed), but I do know that it is not desirable.
As far as battery health; you are supposed to calibrate the battery once a month (let the computer run off of the battery until it shuts itself down and then attaching the power supply.
Other than that, I would just use it and don't worry about it.
My Macbook Pro is about 18 months old; I use it 95% of the time with the power supply, and it is just recently starting to show signs of not holding as long of a charge as before, though not bad enough to replace yet.
I am actually looking forward to having to get another battery so that I have two!