Hi Justin,
1/ You should move this question to the "product and support" section. it's a miracle I saw it, as it is in the "Community Feedback & Help". May be Scott K. Wilder may help relocating it.
2/ To answer your question : no, you do not need to add filters. And you do not want to add trigger as the smart campaign you use has to be a batch campaign. The only exception is if you want to add filters to filter OUT some leads and prevent them entering the flow. Also remember that Marketo will not send the lead to the program if the lead is already a member of the program. This also means that you have to make the lead a member of the program with a "change program status" flow step.
EDIT : Hi Justin Plappert, although you apparently do not need to add filters, the doc says you should add a "Member of Engagement Program" filter. So the recommendation is that you add that filter.
-Greg