Supporter help


I have Supporter installed and have two questions regarding it.

1) How can I change it so that users with only the Author role are able to access the supporter module (at the moment it is displayed there but cannot be opened or anything) I need this as the user that is set to Author is the user who is paying for the service and to pay they need to access it.

2) How can I change the period of subscriptions (I would like to change 3 months to 2 months instead)