Hi @Bradley 

We currently have a save and continue option within the My Nintex features that have just released.

The form will need to be authenticated and enabled for MyNintex in the start configuration:

After that you edit the form and click on the Action bar at the bottom where the submit button is located, you should see Save is now an option to use. 

When using MyNintex you can choose to submit a form but also save and continue that would then let you close the form and view it as a draft.

As for influencing the page navigation, I believe this is something that is currently in the pipeline, either through a direct feature capability or at the very lease possible as a part of the introduction of custom code into the forms capability.

Hope this helps

Jake