Yes you can. Just go to 'My Subscriptions' in your account and click on 'Change Flavours'
No, eBook subscriptions cannot be paused.
Yes you can cancel your auto-subscription by going to 'My Subscriptions' in your account and clicking on 'Change' under the payment details.
With a subscription you are entitled to 3 eBooks per month. You will be able to access these by logging into your Account and navigating to eBooks.
You cannot switch. You need to cancel your current subscription at the renewal date and sign up to the new subscription product you want.