I bougth adult tickets online. Can I use my cellphone to show the tickets?? Or I am enforced to print a hard copy of them? Thank you.

Yes you can

Yes you can. It works without a problem.

Yep, saw some people doing that. Worked fine.

Yes. We did the same and it was no problem.

They have a good customer service desk. Im almost certain they'll look at an email or your phone for admission...

You should be able to show them your purchase online. I also believe that they can pull up your purchase by looking up your email address, as well.