The tickets are all inclusive, minus food and souvenir costs, so yes, you can go on any ride or see any attraction with the cost of admission with very few exceptions. The cost of tickets for seven days, plus accommodation on Disney property, and food will cost you your soul, first born child, and a limb of your choice. If you buy the seven day park pass they may let you keep your soul depending on what promotions are available.
... but seriously, it'll be really really expensive. The cost depends varies widely depending on which hotel you want to stay in, whether or not your going to share a room and what type, where your eating, what your eating, and what your buying when your there. But as an estimate, AT LEAST $1500, however you can easily spend over $2000...easily.
Disney is not a cheap place.
As far as the other questions you asked. Disneyland is in California. DisneyWorld is in Florida. Both are the same company and pretty similar, except California has California Adventure Land or whatever that really awful park is, and Florida has Animal Kingdom, which is pretty cool. Other than that, they're similar, but not the same. Some people like the one in California better, some people like the one in Florida better.
It doesn't matter though because from what you've said, it sounds like you already bought your plane tickets. You do know that Florida and California are on complete opposite sides of the country, and it takes a solid week to travel from one to the other by car, right? If your plane ticket is bringing you to Florida, then you should probably stick with the Florida park. Unless you want to buy another plane ticket.
The procedure to visit Disney is to drive there, buy a ticket, and then enter the park. It's not too complicated. If you are staying at a Disney hotel, they have shuttle buses that will take you to the park and back. Use those, because parking there is expensive. Depending on where you're dropped off at, you either walk up to the booths and buy your ticket, or you wait for the tram to take you to the booths to buy your ticket. Then you go into the park. Or, you can buy your tickets online and avoid the hassle. Check out their website, they'll have more information there.