@mac, for example the specific stainless steel alloy they made my refrigerator doors from. Given that they had a choice, I do wonder sometimes what fool decided to make a fridge door non-ferromagnetic?

This looks like an interesting idea. I didn't know this material existed. Reviews at Walmart and Amazon are mixed, but that may indicate that many people don't follow directions then complain... I may have to acquire some and experiment to see if it will work for me.

@ratchetfreak, I would prefer to match the paint and hand-worked plaster texture so that the region where magnets stick does not have obvious edges. Otherwise, I would just frame a sheet of steel and hang it like a picture... which still might be the best alternative.

I've used that Lil Ripper (or a good clone) for ripping open multi-pair voice and data wire. Works like a charm. It didn't occur to me it would work on romex, but obviously it should. It also drops naked into a tool bag without any obvious dangers to other tools or fingers while groping around looking for the right tool.

The LED chip itself will be good down to cryogenic temperatures. But the lead connections and packaging will almost certainly have issues with wide thermal swings since most of the materials used will have differing coefficients of expansion. That said, -20 ought to be permissible for anything sold for outdoor use. If it weren't, I'd look for alternative lamps.

I'd adapt the design of that lift to lift the box... looks like it would be easy enough to duplicate out of a decently supplied hardware store. It won't give you a lot of mechanical advantage, but for a 26lb box you shouldn't need much anyway. You could mount castor wheels to the wall face of the box, and the lift system just slightly off-center towards the wall to prevent sway.

@Tester101, This table gives the ampacity of 24AWG as 0.577A in a bundle, compared to 2.3A for 18AWG, and 3.5A in free air. So the question is whether the low voltage loads (probably relay coils) switched by the thermostat are drawing as much as 577 mA if a single conductor is used, or about 1.1A if two are used in parallel. In any case, typical 24V relay coils are usually designed to draw well under than 100mA, so even a single conductor is likely to be safe, but if in doubt it would be easy to measure with a multi-meter.

Knowing the height today is clearly useful. But don't forget that trees are not static: they grow. You might want to consider a few years of growth into your location planning....