If they are crunchy when frozen they are probably made from regular compound chocolate, not freezing grade chocolate
You should be able to buy compound chocolate "chips" from any food wholesaler or baking supply store. They are the same as used in chocolate muffins
For frozen chocolate to still have a chocolate feel and taste when eaten it needs to be made with peanut oil (or similar) so as to have a melt point more like chocolate at room temperature when frozen
Regular "Real" chocolate can end up being like eating crayons
Real chocolate with a low cocoa butter, but high cocoa solid level generally freeze much better
Chocolate chips often come in 3kg or 5 kg bags, if you are not using them in a hurry, keep the surplus in the freezer :-)
I don't know about perfectly round, but you can do better.
Stick toothpicks in the truffles before dipping. Dip them using the toothpick, let it drip enough to make sure there's not a ton of excess, probably while spinning it a bit to let it cool slightly and make sure it doesn't all accumulate in one place. Then stab the other end of the toothpick into something to hold it with the truffle at the top. (A block of foam works, as does cardboard, though you might need to pre-poke holes.)
This avoids having a lot of excess coating chocolate, which it looks like you're getting a lot of when scooping out with a spoon. There can still be a little excess, but it'll drip down the toothpick, not get smeared all over. It also avoids having to mess up any of the surface by touching it with the spoon.
Beyond that, they'll be as perfectly round as you managed to roll the centers, which is mostly just a matter of a bit of practice and obsessiveness. So they won't be perfectly round, but they'll be a lot smoother and rounder, definitely enough to impress people. You do get a small hole on one side of the truffle, possibly with a tiny bit of excess chocolate around it where it collected against the toothpick, but I don't think that's terribly ugly. Plus as long as a decent fraction are pretty, you can just eat your mistakes.
Here's what a friend and I managed on our first try:
As you can see, they're definitely not perfect. But we got better at it as we went along. A lot of the irregularities are from initial inexperience, variation in chocolate temperature (we didn't have a great water bath or hot plate setup), and simply not having terribly round centers.
Finally, you might want to practice tempering the chocolate a bit better. Having nice glossy smooth surface makes them look a lot cleaner even if they aren't perfect.
Best Answer
Some basic math, assuming spherical candy and the type of foil that fits snugly w.o. twisting the ends (like thin aluminum foil):
I figured 3.14 for Pi would be precise enough, and the formula is:
For cubic candy:
For other blocks (or close enough, e.g. egg-shaped):
Of course, you'll want to have a foil slightly larger that the circumference, as you need some overlap - just add 1/4" - 1/2", depending on how precise you wrap.