There are two ways to do Disney World. Stay in a Disney hotel, or stay outside of the Disney area in a hotel/villa offsite.
Staying at a Disney Hotel
Staying at a Disney hotel makes your holiday super easy and convenient. The downside is the cost of staying in a Disney hotel is more than hotels in the surrounding area. But once checked in, you get free transportation from the hotels to parks (buses, boats and monorails), so you do not need to pay to hire a car, pay for parking and mess around with all that! You get access to extra magic hours, where a park each day stays open up to 3 hours late, or an hour early, just for Disney resort guests. You get to book your Fastpasses 60 days before your arrival, rather than 30. And your magic bands are free!
Staying outside Disney
If you stay outside of Disney, you will most probably need to hire a car to get around. This does give you more freedom, but it also means paying for parking and enjoying the busy Orlando traffic. You'll also have to endure tolls, and there's lots of them. There are some bus links to the parks, if you don't want to drive, however this is yet another cost and means you'll have to work out the timings for any plans and reservations. Staying outside of Disney is also a lot cheaper, as Disney hotel prices are marked up considerably. So if you're on a budget, this method may be better.
We enjoy staying in the Disney hotels for a more immersive and stress free experience. Of course if you plan to spend some time outside of Disney's parks and explore other theme parks or shopping malls, it may better off spending at least some of your time offsite. If you stay in a Disney hotel the entire duration of your holiday, but want to go off to the malls or other parks, you can get a taxi. Taxis cost about $50 each way to Universal and Florida mall. There is a Lynx bus service from the transport and ticket centre, although you have to jump through a lot of hoops to get to your destination. (Keep in mind Disney don't really want to make it easy for you to go and spend your dollars elsewhere!)
Do I have to plan every aspect of my Disney holiday?
The days of being able to wing it are over. People think they can just turn up on the day, get on the rides they want, and get into any restaurant they want. It is strongly advised that you plan out and book your restaurants 180 days in advance, and your fastpasses 60 days in advance (or 30 days if not staying in a Disney hotel).
Some people don't like planning a holiday to the extreme, and I get that. But you will have a much more stress free time when you're there knowing that you've got everything sorted.
Just because you've booked some fastpasses for a day, it doesn't mean you're completely tied to that park. If something else comes up, or you want to go somewhere else, you can. You don't get punished for not showing up to your fast passes. Bear in mind that if you go to another park you can't book fast passes if you still have outstanding passes at another park, you will need to cancel them. If you're wishing to just change a time for a same attraction it's highly recommended to check the availability before you cancel an existing booking. Once you have used your three fast passes you can book more, one at a time.
Planning your restaurants (if utilising the table service credits) in advance is an absolute must. There are restaurants, like T-Rex and any character dining places get pretty much fully booked as soon as they become available 180 days before. You need to give at least 24 hours notice if you don't want to eat at a booked restaurant, else you will be charged $10 per guest. This does not apply to quick service restaurants.
Planning your Disney trip might sound stressful but if you stay calm it adds to the fun! 6 months before you go you get to choose your restaurants, then at 60 days before you choose your fastpasses, and next thing you know you'll be there.