I agree. If you want to do all quests, it should include everything that you can get to the quest log without special requirements like DLC (I don't know if there actually are quests like that). If you want a category that only does hunts for example, you can do all hunts category or something.
The speedruns don't really grind at all so it's definitely not necessary to grind. However, I think you're "meant" to do some missions in Chapter 11 which would naturally give you some more CP. If you don't, there's a big difficulty spike in Chapter 11. When I play casually, I don't typically grind but I just do some missions and fight everything along the way. But even that is not necessary as seen in the speedruns. Answering the question of what you're doing wrong is hard without knowing what you're actually doing.
Little bit late to the party but Xbox360 has separate leaderboard on another tab for the loading/disc swap differences
So what counts as "fragments of the run"? If you drop some frames, is your run not legit?