Thanks for your feedback.
Regarding the first question, I think that we need to show a success state, not necessarily a success screen. Success state might be something as simple as green checkbox that notifies users that the operation completed successfully.
Thomas Hallgren, thanks a lot for your question! I think that gender selection is interesting case — it can be considered as an exception for the rule “Always Offer a Default Selection” — so I think it’s better to use radio buttons without offering a default selection + add a plain input field next to Female/Male when users need to use custom gender…