I can’t say I’ve had experience with Blu-ray burners on the Mac, but I have had a bit of experience with external drives.
First things first: the USB2.0 implementation on Apple’s older laptops should support a solid burn to a Blu-ray disc, though it won’t be all that quick. (6x may be the upper bounds for that).
The drive sleeping issue: OS X does have a quirk when putting external drives to sleep. It seems that, depending on the chipset, the Mac can be cycled through a few sleep cycles & wake-ups before the optical drive doesn’t wake up again. If this happens, though, all you must do is power cycle the drive and it will be good to go. (I would say to go ahead and disconnect the drive, anyway; that seems to work around the problem). This happens with many drives, so no worries about going specifically for a Pioneer.
One other thing of note is that, with a disc in the drive, you must use the system “Eject” command from within whatever application you’re using, or install the persistent menu bar eject icon (Google search on that: https://www.google.com/search?q=add+eject+to+os+x+menu+bar). The eject button on the drive itself is ignored as long as a disc is in the drive (even after the Mac is turned off, in some cases).
Right, then. Next up, OS X since Leopard (I believe) supports all optical drives for the use of CDs and DVDs. You could still use a BD-RE drive with CD/DVD media as is normal and be perfectly fine. The Blu-ray limitation, as I understand it (and as you’ve noted), means that none of Apple’s software will play back a typical Blu-ray movie, and you can’t burn to a BD-R/RE disc with any of Apple’s software, but you should still be able to browse previously-written discs such as data discs. (Don’t quote me on that last part).
Backing up your photography shouldn’t be a problem if you have a capable burning program; Roxio/Sonic Toast 10 and newer support Blu-ray writing, at the very least, and some other options may exist that I don’t know about.
Choosing a good Blu-ray ripper might be a different story. I know they exist, but I have not paid much attention to which programs are the best. I would start with the following links, personally:
All of those links point to MakeMKV and Handbrake, but this forum has quite a few fans of DVDFab, who also seem to have an OS X version. I would go with them should MakeMKV not work: http://www.dvdfab.com/index.htm