PayPal subscription integration workflow

PayPal subscription integration workflow

I am looking to offer subscriptions on one of my websites, but am a little
confused on exactly which PayPal services I need to use to accomplish
this. I'm not looking for any code to help me here, just a little guidance
on how the entire process should play out and whether I'm using the
correct PayPal tools.
So, users sign up for an account on my site and receive a free 30 day
membership (I know I can set this in PayPal, but I do not want to ask
users for credit card/billing information at registration). Within that
initial 30 days, users have the option of subscribing and keeping their
account active by entering their payment information directly on my site
using PayPal Payments Advanced. If the user still has, for example, 10
days left in the complimentary subscription, I do not want them to be
charged until after their complimentary subscription expires.
Is there a way I can specify the date I would like the subscription to
start when submitting the subscription information to PayPal? Or would I
need to use a simple 'Buy Now' type of transaction for the first payment,
and then set up a subscription?
Am I also correct in assuming that by using PayPal IPN I will receive
relevant subscription information, such as when I receive a payment, when
a customer's payment could not be successfully completed, etc., so that I
can take the necessary administrative actions on my site to activate or
deactivate their accounts?
Also, can I use "Modify Subscription" buttons to allow users to update
their credit card or billing information, or would they need to directly
login to their PayPal accounts for this?
Finally, would all this still work as intended for users who do not have
PayPal accounts?