As to the Cloud, I don't want to back up to something I neither own nor control...!!
iCloud purpose is not for backing up computers to at present, and I would not personally recommend it, if fact I would always back up a computer be it Apple, Windows or any other machine to an external hard drive that you personally own and is in your possession. This is not because I do not think that data for individuals is not safe on ICloud but mainly because if you do use it as a back up medium then you are reliant on 3rd party infrastructure, namely the Internet, it is not impossible for data corruptions to occur across this medium. Putting Photos on ICloud enables you to access them and share them across all your devices, that still means you should back them up as alread said along with your other data.
Jays you can continue to use Aperture, although edits made with it to photos will not be reflected in Photo. I am going to do a bit of investigation on this as I suspect their may be a work around.
