I'm not qualified for the Search & Rescue recommendations, but as in the thread posted above by Robert, the CS shovel gets my recommendation (standard disclaimer, no affiliation with CS). It is compact and sturdy, the edges come factory sharpened and can be further sharpened to your liking. Because of the sharpened edges you can use it in a pinch as a hatchet or short machete (obviously not as good as an axe or machete but it will get the job done) and "cuts" into hardened soil with relative ease. I would think it would serve for your other purposes as well. Mine has served me well for the last 15 years give or take and has taken every bit of punishment I have dished out. Remember that it is a compact shovel so the shovel head is relatively small. If you need it for snow removal it will get the job done but it may take a while. Hope this helps.

Edit: +1 on nighthiker's recommendations for snow removal. If that is less of a concern and you need something sturdier, I still recommend the CS.