Yes. Your ticks are saved privately in your browser, so the list is exactly as you left it when you come back. "Reset for next gig" clears the checkmarks while keeping your items.
Yes. Add anything you like to any category, and remove the ones you don't need. Your custom list sticks around between visits.
Yes. The Print / Save as PDF button gives you a clean one-page checklist to take to load-in and tick off by hand.
No. There's no sign-up and nothing is uploaded — the whole checklist lives in your own browser.