How much is the approximate time to spend ?

Plan 3. More if its busy and you want to experience everything, read everything.

3 hrs.for sure! Anything less you're short changing yourself. So don't get the fast-pass.

I agree, 3 hours is accurate. More if you read everything and watch every video.

We were there for about 3 hours and saw it all

2 to 3 hours to see everything and even more if you watch all the snippets and participate in the spy mission