Question   How do I setup a test account without someone having to pay?

A. Under advanced features change "Software Is Free" to No. 
Then, on the join page (/join), you can either enter the email addresses of the people you want to give free accounts to on the right form
OR fill out the left form to create a free account.
Also, you can import several members at once from .csv file using the import members section.

A. Yes, you can setup a free trial when creating the billing option.

A. Create a membership then go back to edit it and select free when editing the membership.  Leave it as paid under advanced features and leave all other memberships as paid.

A. On the join page you will use the form on the right of the page to send an email to anyone you wish to give a free account. They will need to follow the link to activate their free account.

A. Move them to a contact group that does not have any autoresponder messages assigned to it.