1. On the " Difficulty and Terrain of Caches I've Found" grid, find 8 of the possible 17 with a rating of "5". You could find 8 Terrains with a rating of "5", 8 Cache Difficulties with a rating of "5", or you could find any combination of the two as long as there is a "5" in either the Difficulty or Terrain rating. Of course you could find a 5/5 Difficulty/Terrain, but it would only count as one of the eight combinations, not two.
2. Most challenges that we have seen make you complete the entire 366 "Finds For Each Day of the Year" Grid. Since this is only a Half-Challenge you only have to complete half of the grid - at least one find on 183 days of the year. It does not matter on which 183 days of the year you have a find.
3. Geocaching.com lists 20 types of caches in the "Cache Types I've Found" chart in your statistics profile. To met this challenge you must find at least one geocache in 10 of the 20 caches types.