Sure, you can plug a blu ray drive into a mac, but there's no software for OSX that supports playback for sony's drm-ridden stinker of a codec. You could however run windows on bootcamp as a workaround. There's probably software for the OSX to just rip the BD to storage, which may just be a perfect solution.
Per dvd v blu ray quality, yeah I can notice the difference. 480 vertical lines of resolution V 1080. On top of that, that 480 is 4:3 aspect ratio, which dvd films tend to not be, creating more resolution compromises. Right now I'm using a 17" laptop screen with 1920x1200 resolution.
Also something sexy about having 7.1 lossless audio
Blu-ray soundtracks - Blu-ray: CNET's Quick Guide - CNET Reviews
Per download v blu ray, I think it's an option limiter. This would rule out netflix discs and the discs i already have or borrow if i forgo a drive for that reason. I also have a speed issue, my wifi provider just doubled their rates to $100/year and I get what I pay for. That's not saying I don't see the logic in doing away with optical media to save space and money, It's just I'm not sure of the best way to get drm-free 1080p movies, and when I do, i'm gonna need a burly storage and backup system as my library is now all in one disk. Piracy solves so many of these problems. How unfortunate, how much easier it is to get music tv and movies illegally, even when the price issue is negated.
Per music, I'm right behind you. Right now i'm in my <=320kbps VBR mp3 stage of my addiction, but if I get that beefy storage and backup, i'll go FLAC and put my cds in mom's attic. I'm real interested to know what my options are for some 12v high quality compact surround sound that does hdmi 1.3.