There is no charge for the Telecard. The calls you make on it will appear on your regular bill.
They are the same card. Global Access Telecard is the official name.
There is another card called the Prepaid card, in increments of $25, $50, $100, etc.
In addition to inexpensive long distance worldwide calling, the Free "Global Access TeleCard" has many features.
30/6 means the first 30 seconds are billed, then at 6 second increments.
60/60 means the first 60 are billed, then in 60 second increments (This is not so good because if you talk 1.1 minutes, you get billed for 2 minutes.)
Yes, it is a bit confusing. They all start with "Global Access", but they have differences depending on:
1. What country you are calling from (USA or international)
2. What country you are calling to (USA or international)
3. Who's phone you are using (your own or someone else's - such as a pay phone)
Most people in the USA would probably want G.A.D. - for people in the US who want to call overseas.