I would like to set up a recurring subscription that has time-limited access as a free trial, then move to recurring payments... but I would like to have no credit card required for the free trial period.... is that possible?
No, if you want it to be recurring, then credit card is required at the time user sign up. In your case, maybe create a Free Subscription plan (with Enable Renewal set to No) with an option to allow users to update to the paid recurring plan. That should work