Hard drive in optibay questions.

What would be better to put into the optibay of a macbook pro 7200rpm or 5400 rpm hdd?

Any significant increase in battery consumption or vibration with 7200 rpm? I thought it may cause a problem under the keyboard (vibration).

Any significant decrease in performance with 5400? My OS will be on my main ssd in the original disk bay.

The hard drives i can get are 6Gb/s, will they cause a problem with the 3Gb/s SATA connector in the optibay?

Can I eject the hard drive in optibay and re-mount it later without rebooting?

Also, when I take the superdrive out, can it be powered with just a SATA to USB cable or do I need an enclosure?

Macbook Pro 15" early 2011 i7 2.0ghz OS X 10.10.3