Is there a way to iron out the creases from folding?

Please use some Nails,Hooks or Ropes to stretch the screen for few days, and then the wrinkles will be less. And also you can hand wash and iron it but remember not too hot. In fact, the folding wrinkles will not affect projection, thanks!

Can use pvc screen outdoors? what do i need to set it up?

Yes, you can use it outdoors. I hung mine up with bungee cords. It has grommets you can use to attach clips. You could also use some adhesive Velcro. I hung some black out fabric on the back of my screen to be sure the picture is crisp.

Can this work for rear projection?

Yes, this Canvas screen is Perfect for rear pejection and front projection.

How do I clean the screen if it gets dirty?

Hello, please wash your 150 inch portable projector screen as below: 1. Let the dirty part of the projection screen soak for about 10-15 minutes in soapy water. Its grommets are made of iron and water makes them rust easily, so try not to get wet. It's best to wash where it gets dirty and not wet the whole 150 inch outdoor movie screen, especially these grommets. 2. Wash the dirty part by your hands with little detergent. 3. Rinse the washed part with clean water. 4. Wring half dry and straighten your outdoor porjector screen, and then hang it out to dry soon. If the 150" folding projector screen is wet, it should be dried in time. If it is wet for a long time, it will easily be out of shape. Many thanks!