Starship weighs 120 tons empty, so yeah, getting Starship to the moon would require just as much enegery (delta-v) as getting the space shuttle to the moon. Read this thread: https://greatawakening.win/p/19BtGb0V0j/elon-musk-proves-the-apollo-11-m/ (some other space nerds sum up the math nicely for those who dont understand).

For the van Allen belts, mehhhhh, Polaris Dawn flew through them last year and the crew said they got a dose similar to being on ISS for a month, and astros routinely spend months or even years on orbit. So not really a big deal.

Rockets definitely work in a vacuum and they're one of the only proplusion and control mechanisms that do - you're thinking of paddles, rudders, jet engines, propellers, rotors, and wings - none of those work in a vacuum.

I wouldn't say that starship's nine integrated test flights to date have been failures. They caught the booster from mid air, and not just once. Every flight they learned something since the last one. This is basically a Saturn 5 class super heavy lift vehicle but fully reusable. Let that sink in for a moment. Saturn 5 class super heavy lift, but without expending a single part.