To answer your last question: yes.
Regarding the previous question, it's because the temperature at which the cocoa butter in the chocolate crystallizes affects the overall consistency of the chocolate. If you've ever eaten a chocolate bar that was left in a car on a hot day after it has cooled down again, and who hasn't, you'll know about this. Sometimes chocolate tastes fine but has a definite 'grittiness' to it: other things being equal, that's usually because the cocoa butter crystals are too large.
Cocoa butter has a number of different crystal forms, each of which will have a slightly different effect on texture and melting point. When melted chocolate sets, the cocoa butter crystallizes, and it will generally all crystallize with the structure that it starts to crystallize with. (This process where crystals start to grow is called nucleation.)
So you want to have control over the temperature at which crystallization starts. The optimum crystal form for nice chocolate will tend to predominate when crystallization starts somewhere between 18-25 degrees C (around 64-77F).
So if you think about it: when you add room temperature stuff (like a pretzel) to chocolate that is considerably hotter than room temperature, the resultant temperature on the surface of that pretzel will likely be way higher than 18-25 degrees. On the other hand, if you are dipping an item that is significantly below room temp, then your chances of hitting that window are much higher.
The surface structure of the thing being dipped can of course make a difference to crystallization as well, but for normal purposes that is marginal. To put it another way, it doesn't matter what ingredients you're dipping - temperature is key!
I think most chocolate is already tempered when you buy it. Assuming that's the case with yours, you just need to be careful not to break the temper when you melt it. That means not letting it get too much warmer than its melting temperature. If my memory is correct, you have to keep it below 125 deg. F to avoid breaking temper.
Coincidentally, I mixed pure cocoa powder and honey earlier this evening (in a glass of hot milk). I found that to get it to taste good, I had to use about 3 Tbsp of honey to sweeten 2 Tbsp of cocoa. Honey is usually about 17% water. I don't know for sure whether that will cause a problem for you, but I suspect it would. As you have already discovered, it takes a LOT of sugar to make chocolate sweet. I don't think you'll be able to make it solidify using honey.
I'm curious why you seem to be avoiding sucrose (table sugar). I guess there must be some reason why you got no-sugar-at-all chocolate. Are you interested in stevia because it is lower in calories? If so, you might consider pure sucralose. It's not usually available in stores, but you can order it online. I recommend pure sucralose instead of splenda so that you don't have the extra maltodextrin filler getting in your way. 1 gram of pure sucralose is enough to sweeten 250 grams of cocoa powder, so if you know the ratio of cocoa butter to cocoa solids in your chocolate, you can calculate the right amount of sucralose to use. I guess if you're thinking of using honey, you must not be worried about calories, though. If you're just looking to create a little more exotic/different flavor, you could use turbinado (e.g. Sugar in the Raw) instead of regular sugar. I think it will solidify a lot better than honey.
By the way, how are you planning to coat popsicles in chocolate? Won't the molten chocolate cause the popsicles to melt and turn the whole thing into a mess? Maybe if you got the popsicles down to liquid nitrogen temperatures before dipping them it might work....
Best Answer
Chocolate is an odd substance when it comes to melting and hardening. When chocolate hardens, its melting point will end up being just a few degrees higher than the hardening temperature.
When chocolate crystallizes at high temperatures, it forms a strong, dense crystalline structure that, texture-wise, is quite brittle. Most bought chocolate (baker's chocolate and chips) is already tempered, but when you melt it, you break down that crystalline structure, and if you harden it at room temperature then it ends up forming very weak crystals that will melt in your hand.
If you use a special coating chocolate (couverture or the lower-quality compound chocolate) then you don't need to worry so much about tempering (although it's still a good idea), but if you use ordinary chocolate and don't temper it then your coating will end up being messy and wet and rub off on your hands while you eat it. It might even melt while stored.
Tempering is the key to making a room-temperature-stable chocolate coating. If you don't do this, you'll need to keep your pastries refrigerated until they're ready to consume.