1. It is needed to be able to downgrade a user to "no plan" if the system allows "no plan for free registered users" without cancelling or deleting a subscription. You can't delete it, but you can change the text using the language plugin and editing the string there.

2. The radio will appear if this is a possible choice

3. Yes, what Kyle wrote can make sense in regards to making the none disapear:

Set both the following to NO:
Allow Free Registered Users (without subscriptions):
Create Subscriptions also for free lifetime plans:

That way the system allows "no plan for free registered users", making the none disapear (see 1), but still doesn't allow free registered users if that's what you want.