3.16 The word for ought/owe is "ophell-oo" which has a sense of being bound and obligated (more than a casual "should").
3.16 The word for life here is "psyche"
3.17 The word here for "means/ability" is "bios" (as in biology); in 3.15 in fact, the word zooeh (as in Zoo) is found. This in three consecutive verses, we have ideas about life: eternal "zooeh"; a "psyche" that is laid down; and "bios" to provide for others.
3.17 The word for compassion here is splagchna, which means intestines. The idea of the word is that compassion means your gut wrenches.
3.17 The word for world, "kosmos" is often set at odds with God in the Johannine writings. Here though we see that the world can have a purpose, to help others.
3.22 There is no word "whatever" in this sentence. It simply says, "If we request this, we will receive." The "this" is less likely "whatever" and more likely the rest of the clause -- doing of his will. (The later clause begins with "hoti" which may be translated "because" or "that" so "If we request this, we will receive from him that we keep his commandments.)