Can I create repeating data sections and mass submission?

Yes - you can.
Here is a scenario:
Say someone wants to display a list of upcoming events and allow his fillers to indicate which events they would like to attend by ticking a checkbox against several items. Once the filler submits the form you could have a campaign member record created for each event he selected.

In a nutshell this is what you have to do:
- Add a section element to your form.
- Drag a textbox element and a checkbox element into this section.
- Make the section repeated.
- Set a Salesforce Get integration that connects with the 'events' object and loads all of the upcoming events names into the Textbox.
- Now set a Push integration to create this member under each selected event:
- Choose the 'Events' object and set an 'Update' action.
- Create a child object under the events object: campaign member.
- Choose the 'create' action so a new member will be added, 
- Specify a Rule condition in this Push integration to make sure that only if the checkbox is turned on, should the member be created.
- Save the integration and the form and you are set to go.