With my website's membership, can i access all the websites in the network?

No. Each site behaves independently and requires it's own membership.

However, once you create a user name at any of our websites, you can continue to use the same user name across any other website: You do not need to create a different user name for each website.
Bear in mind that each website will still request it's own credits or membership to be able to access all its features.