Hi Elizabeth,
Let's discuss these points:
(1) Think of these Subscription Lists as "bins" or "topics". The recipient/customer doesn't know what Marketing List(s) they are on in your CRM, but they probably have an idea of what types of emails they would/would not like to receive from your organization. It is fine to constantly creating new Marketing Lists, but it is recommended to associate these Marketing Lists with a Subscription List, in order to keep your recipients' preferences in mind when you construct and send out your emails.
Your Question: As I add new static marketing lists to a subscription to meet my needs, it would automatically include anyone who had opted in since the subscription was created, correct? As in, it would take the most recent information as of the moment I create the marketing lists (typically, moments before I actually send the email)?
Answer: When ClickDimensions sends out the Email, at the time the Email Send is executed we treat this as a mail merge. As the message goes out to each recipient, we are de-duplicating the email addresses it is sent to, merging the correct Freemarker code for each recipient, and verifying each recipients' subscription preference. These preferences are verified into account not when the Marketing List is created, but when the Email Send is sent out to the listed recipients you're trying to send the email to. You determine who is on the Marketing List, whether they have opted out of the Subscription List or not.
(2) Your Question: Furthermore, are you required to link an action (such as it updating the marketing lists within the subscription with the opt-ins) to the subscription form. If I don't include those actions, it will still create the proper information within the contact record? It just would not take an extra step to update the marketing lists associated with the subscription, correct?
Answer: No, linking an action is not required when creating your Subscription Management Page, but it's nice to do to ensure that if someone does wish to receive a certain type of email, they are added to a Marketing List that has associations to that particular Subscription List. If you do not include actions, it will still create an opt-in or an opt-out for the Contact record in CRM, but that person just wouldn't have a particular Marketing List to be added to in that instance. However, if they are added to a different Marketing List in the future with Subscription List associations, their preferences certainly would be considered when you send an email to that Marketing List.
I recommend checking out our two Help articles that illustrate the different ways to handle opt-ins: Workflow or Action:
Manage Subscription List Opt-Ins with an Action: http://help.clickdimensions.com/manage-subscription-opt-ins-with-an-action/
Manage Subscription List Opt-Ins with a Workflow: http://help.clickdimensions.com/managing-subscription-list-opt-ins/
Managing your Subscription List Opt-Ins with a Workflow requires a little more set-up on the front end, but overall it keeps your Marketing Lists much cleaner.