1. No, leaked files generally do not contain guides on how to optimally abuse their intellectual propety.
2. You have the programs that use them, go research. ...but should be a list of a function events and handlers in this forum somewhere for both GF & C4, most are self explanatory.
3. See above.
4. myself is the AI instance\class where code is executed, which doesn't always mean a NPC instance but could be a Makerinstance also.
5. A CSharedCreatureData struct within AI class, for npc instances.
6. Yes, see 2.
7. Load time, not run time.
8. If declared properly, yes.
9. See above.
10. A watch list, most likely used with l2logd. Fairly pointless for most private servers. Probably monitoring measures if large quantity or rare items suddenly explode within the game world.
11. Same as skill_pch - just with different data.
12. Same as above, with quest.