Yes, you don’t have to wait until the end of the 14-day trial period. Moreover, the subscription you will buy will be extended by the number of unused days from your trial period.
Yes, your service will wait for you blocked.
Click the ‘extend’ link next to the expiry date of your service in ‘Your Account’ section.
Yes but only for a higher one. Click the ‘upgrade’ link under the name of your current subscription in ‘Your Account’ section.