Regarding Enrollment, there are a few things to be aware of.
First, if you enroll 10,000 contacts into a sequence either manually or via SmartList, all contacts will be 'Enrolled' and show up as enrolled on the Sequence Stats page. The records will be "in-queue" until the sequence begins for each record, and the sequence beginning for each record is dependent on your settings (my example in the screenshot below shows 10 enrolled).
Even though the records are "enrolled"...when the sequence begins for each record depends on your sequence settings.
The Daily Enrollment Limit will determine how many contact records that are "in queue" will begin the sequence each day that you have the sequence set to send.
With the screenshot below, 5 new records that are "enrolled" and "in-queue" will have the sequence fired off each day Monday through Friday.
You can also visualize everything a bit more under the Enrollment Tab, under your sequence, which will break down all records in the sequence, and which ones are active, in-queue, and have completed the sequence.
Furthermore, this tab will allow you to easily see who has opened, clicked, or replied to any emails from the sequence.