Yep, anything below a 6 means some kind of unwantedness happens, how bad it is depends on position. In a Controlled position, you might just have to try again in another way, while at Desperate, you could face serious harm straight up (always with the player's ability to resist of course). In Blades in the Dark it's all laid out starting on page 23.
1-3 is both failure and a consequence. Position is what happens on a failure, Effect is what happens on a success. On 6 you get your effect with no consequences from position, on 5/6 you get both, on 1-3 you only get a consequence.
Depends on what you're going for. If there's already a product in a similar genre / style to what you're trying to build, it might be quicker to start from there.
Nope. You framed Stitch as an example of some larger trend in FitD/PbtA games having super bad playbook names, and I pointed out how that generalization doesn't work. You don't have to agree with me, but don't make a lazy, sniping generalization—which also shows just how little experience you seem to have with those games—and then get ever-so-offended by pushback.
I agree with @MarkB that it might be quicker to hack something closer to your ultimate goal, but if you really want to dig into what makes FitD unique and, for some types of games, super effective, it's worth reading Blades in the Dark. The PDF goes on sale or is part of bundles on a regular basis. It's a good game to own, even if just to look at what kicked off a bunch of others.
If you have a concept that fits it's structure (phases of play including downtime, crew, concise adventures, etc.), I'd look both at the original that spawned these other ideas, and at least one of the other FitD so you can see what types of things change and what they kept as consideration for your own updates.
