On triggers: Cron, GitHub (PRs, issues, @twill mentions in review comments), Slack, Linear, Notion, Asana webhooks, plus CLI and web. Our PR-comment workflow is you would have to tag @twill with an instruction. That being said, you can also setup a daily cron on Twill that checks PRs with a specific label like Confidence Score : x/5 and tell it to auto-approve when 5/5 for example.
On setup scripts: Per-repo entrypoint script, env vars, and ports, all accessible on the UI. There is a dedicated Dev Environment agent mode that you start with to setup the infra. You can steer the agent into how to setup if it gets stuck. So this should be smooth. The agent can also rewrite the entrypoint mid-task.
There is also a Twill skill you can add to your local agents to dispatch tasks to Twill. Meaning you can research and plan locally using your CLI and delegate the implementation to a sandbox on Twill.