It's about 35 miles, but you're travelling with the weekday rush hour so it will take some patience. As others have said, expect an hour or more. On a Saturday/Sunday/Holiday you might get lucky and it could take just 40-45 minutes.
I wondered the same thing. Can you prebuy tickets or just buy them there? Also Is it worth it. we have one day that might be fun to go there. Where do you stay if you were to leave DL and go there next? TIA