Regarding the afternoon turbulence, as you surmised it's a summer time thing. Even then I never hit severe turbulence in NM. In fact, not even moderate. My primary flight instructor told me that he's taken a smack upon a canopy in Diamond once hard enough that it knocked him out. But that was in Oklahoma, not in New Mexico.
I learned quickly to steer to the upwind side of mountains, in order to avoid the orographic turbulence. But you're going to be high enough for that not to matter. Except for the wave, of course.
As far as navigating to Scottsdale, I don't see just why that is a problem IFR. I only visited Phoenix area VFR and thus I had to be on a sharp lookout for the Class Bravo versus the rocks. But if you're IFR, all you need to do is to slow down ahead of time, so that you can lose altitude without gaining speed, right? I fly an E with electric flaps, so if I get under 120 mph indicated, I'm golden: as soon as the airplane is dirtied, I can dive as much as I want.
About the survival, make sure you have water and trash bags. Most of the route is mostly flat. Now, coming up to Phoenix the terrain gets inhospitable: steep slopes, woods, reservoirs. That area is unpleasant, and the city itself is better only marginally. But it is what it is.