Do I have to update my PS3?

Well since PS3 came back online because of the hack that crippled PSN, I was wondering do I update my PS3? I haven't go online since I bought the PS3 in march. So please I need some help. How long does the Update take? and Is setting up a account straight forward? any fees? and do I need a credit card to do so? More so, are all updates mandatory? Like Do i need it? I hear they update every couple months. thanks. Please give me a site for sources or if you're one of the millions who know about it. thanks.