Was a whiteout, so now I'll need a GPS so I don't walk off a cliff.
No technology in the world can prevent you from walking off a cliff in a whiteout if the terrain is rough. Of course, a GPS can assist your efforts to stay in areas where cliffs are fewer.
But as an experienced solo hiker I bet you knew that already, didn't you? Nevermind, I just took advantage to blow off some steam on a subject dear to my heart: Overconfidence in technology. Trusting a GPS is great as long as you don't have overconfidence in its accuracy. Being just 3 foot off trail is deadly many places...
You said it yourself to the ranger: "How would you know to look for me?" Most people that live through an avalanche are saved by their buddies. This is where avalanche beacons can and do make a difference for those dedicated enough to use one. For your purposes, it is just a body locator service: All by yourself in an avalanche, you'll be dead and long gone before anyone reports you missing. But locating your body is no small thing - it saves hundreds of man-hours of searching and improves the grieving process for your relatives and friends.
Oh, and I'm pretty sure no PLB in the world will ever work buried in an avalanche - snow and ice are not good mediums for radio transmission.
I say avalanche is all about knowledge and avoidance, in particular for the solo hiker. But ah, the joys of skiing the very slopes that are most prone to avalanches...
3. GPS, guess I'll get one of these finally, are there any combo units with emergency beacons?
There are PLB's with GPS in them, read the threads about SPOT on this forum. But those are (to my knowledge) not suitable nor intended as general purpose GPS. I suggest you keep GPS and PLB separate, that way your every day routine (GPS navigation) does not empty the batteries of your emergency life line (the PLB).
4. Avy beacon, will any of the above work instead?
To my knowledge: No.
But there are miracle stories about people being saved with reflections from cell phones when searched for with Recco-equipment. Doesn't sound very reliable in my book.