I would suggest not to do that if u want to enjoy all the rides
Yes. You can take a back route in and out of HP without going on the train. We walked back to Hogsmeade from Toon Town and the Universal back lots/Hollywood. We took the train also, but you can walk it. Some rides were a 60 minute wait, so you might want to choose your rides wisely for the time you have available. We were there from 4-12pm, and didn't ride any of the water rides. We spent most of our time in Hogsmeade and London, and then skimmed through the other areas, riding what caught or eye. They do have fast passes, and you would definitely want to take advantage of that in order to do all you want in one day. Ideally, I think 2 days are best.
Yes. You need a park to park ticket and transport in HP traen from one to another
It depends on your energy levels, how much you want to do and see and how long you are planning to spend queuing. To give you an idea : We did the island of adventure park on a school day, in the value period - so at a time when there were less people in the parks. We did not try everything, for example none of the marvel heroes rides, but we tried admittedly a lot of all others, arrived at 10am and left exhausted after 7pm. Queues were a manageable 10-20 minutes.
Yes you can .. but you need to schedule your rides properly. You can buy fast pass to avoid lines.
Yes but it obviously depends on which rides you want to ride and of course, how busy it is. If you want to do both, be there for an 0800 start, at the latest. Enjoy!
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