When I started designing playbooks for my BitD hack I started with the originals and basically renamed all the special abilities, actions, and items to things that were more representative of my setting. Since my setting didn't have anything that could be considered ghosts, spirits or demons, I had to make a few special abilities from scratch and slot them in to make up the difference.
Afterwords when I got to be more comfortable with with game and my setting I started remaking the playbooks from scratch. A big help with this was finalizing all the rules changes I was making to the BtD system. Playbooks essentially allow each character to bend and break the rules of the game, so I needed to know what those rules were, including what I was adding and what I was leaving out. Also it was handy knowing what the standard items and playbook items where available to each playbook so there wouldn't be too much overlap between different playbook items, and what the items let you do and what special abilities each playbook had.
For me, making a cyberpunk hack, I thought a lot about genre tropes and the sorts of characters you see in those stories and what it was about them that moved the plot forward or provided interesting opportunities and actions within the story. Obviously there would be a Hacker playbook, and also someone who was good with hardware. Then there's the suit or ex-corporate person who is good at setting up meetings and lying to people, etc. etc. Once I knew what sort of character I wanted each playbook to represent, then I would start assigning starting action dots that made sense for the sorts of actions that character would be doing most of the time. The Hacker wants to be good at Hacking, the Fighter wants to be good at Assault, the Hustler wants to be good at Connecting with people, etc. Then I would brainstorm some special playbook items they should have: The Hacker should have a fine custom computer and some special armor that protects them from harm when they hack. Oh, and you know what would be cool? Cyberpunk films often have awesome soundtracks so lets give this playbook a custom soundtrack item that lets them set the mood for whatever is happening during the scene.
For me special abilities represent a few distinct possibilities:
- Get a bonus die or increased effect in a limited context.
- Use special armor to push yourself or avoid a consequence suitable to what that character is usually doing
- Some kind of bonus (+1d, increased effect, or fill in additional clock segments) towards at least one downtime activity
- Permission to twist or change the narrative
This is pretty much what you've already covered. Some special abilities are evergreen, like the Cutter's ability "Not to be Trifled With". Most hacks I've seen have an ability like that or something close to it, because you want your fighter to be able to tangle with a lot of people at once. That's cool. Don't feel like you need to redesign the wheel with each playbook, there's a lot of solid structure you can build around.
Honestly it already feels like you have a pretty good handle on how to make a playbook. The only advice I would give is to think about what you want each character to do in the narrative of the game and not just in the mechanics, and to make sure you integrate any rules changes you've made into the design of the playbooks and special abilities, if appropriate.