You have to add this courses into your profile.
You can start your subscription by adding either your paypal or credit card details. You can cancel your subscription any time.
You can easily cancel your subscription my going to your profile and clicking Cancel Subscription
Your certificates for the courses completed by you will always be there.
You cannot download the videos but can download all source code and other reference materials.
There is no limit. You can take any course you want
We will be launching the group licenses very soon. Currently there are only individual licenses.