1. I'd be interested if they have instrumented crash dummies inside for this sort of thing. I'd imagine they'd get some whiplash, but that's a lot better than blown up.
3. Not necessarily. Their first flight had the same tower. Presumably for engineering access to it when it's stood up. https://youtu.be/rEdk-XNoZpA?t=17s
If you're properly restrained, you can survive absolutely massive g-forces. John Stapp survived 46g on a rocket sled; Indycar and Formula 1 drivers regularly walk away from >100g crashes. Assuming they're using a proven seat and restraint design, the capsule's own sensors should provide satisfactory data on survivability.
Just to put some perspective on this, you are likely unable to survive >9g when experiencing it for more than a few moments, definitely so if you lack proper training for high Gs (there's a few techniques that help to avoid harm). The higher the G forces, the smaller the acceptable time scale is. In a crash, you will only experience such forces for a few milliseconds. Well-trained fighter pilots can handle ~9Gs for a few seconds. Apollo reentry had like 6Gs for ~50sec (take with a grain of salt, very rough numbers), which is brutal but manageable.
And – no matter what the designers/operators say – in a roller coaster, you will never experience more than 1.5Gs for more than a fraction of a second. If you ever thought you experienced G-forces comparable to a rocket launch, you haven't, unless you had the chance to test/train in a centrifuge.
3. Not necessarily. Their first flight had the same tower. Presumably for engineering access to it when it's stood up. https://youtu.be/rEdk-XNoZpA?t=17s