The credit card is invoiced automatically if you are using the monthly subscription.
You can actually change a language on each level. The ability to change a language is hidden on the Change Hero page. So click a level, then click Change Hero, and you’ll see the language options.
When you reset, you’ll keep all gems gained through purchases – this includes those from monthly subscriptions (3500 / month), yearly or lifetime memberships (42,000), or direct gem purchases. All gems earned from completing levels are removed (because they’re no longer complete!).