Hi Laura,
I’m a Security Engineer here at Monzo.
Thanks for your feedback. Security is something we invest a lot of time and energy into and at some point I’d like to create a page on the website to explain how we protect your money.
On your first point:
If you have a Touch ID enabled phone then you can enable Touch ID to access the app. However, we see this as a privacy feature, not a security feature. If someone has access to your unlocked phone then they can top up your account but they cannot send any money without further authentication.
On your second point
Again, if you have a Touch ID enabled phone then you can (after activating Touch ID) view your pin in the app. If you don’t then as @anon38211169 says you can ask customer support and they can help you out.