Bubble apps aren't just marketing pages, so where you add the script depends on whether you want app-wide tracking or just certain pages — Bubble supports both through its SEO settings and page-level HTML elements.
Yes, by default it applies app-wide, including pages behind login — if you only want to track public/marketing pages, use a page-level HTML element there instead of the app-wide setting.
No — Orbit's script only reports pageviews and basic engagement metrics, not custom events tied to Bubble workflows. That would need separate event-tracking instrumentation.
No — header scripts are unrelated to Bubble's workflow/capacity-based pricing; it's just a script tag served to the visitor's browser.
No — the header script setting applies at the app level regardless of which domain visitors use to reach it.