Can I acess epix via roku box app??

Yep.

Yes if....you subscribe to it via Dish. Otherwise it's a 14 day free trial with ROKU. Link your Epix on ROKU with your DISH account #.

Absolutely! I have been using the heck out of this app on Roku. BTW as far as I can tell all of the content on EPIX is on Netflix too.

Not all. There is a vast cache of older movies not on Netflix and Epix shows newly released movies 90 days before they show up on NF.