No spoilers, don't worry.
The first part was fairly straightforward but required patience and attention to detail. When I had the A-HA moment about the general nature of what we're looking for, the online references to specifications for such a thing were of great help. I am definitely going to hide an "Unknown" type Geocache using this method sometime soon!
As for the second part, I do not believe it can be solved in the manner that it makes seem obvious. At any rate, not without sheer luck. I found a quick & dirty way to solve it, instead, and I do believe that was the intention of the puzzle-makers.
Now I am stuck on the third part. Still not ready to throw in the towel, however. Check in with me after Christmas.