1 pointTry out the "Restricted Profile" feature in Android under Settings -> Security. You can Google for "android restricted profile" for more information. I don't believe Roku has the controls either.
1 pointIt is just webmail, so it should work in Chrome (browser). If it doesn't work, then contact RR. According to the link you provided: You can get in touch with our tech support if you have issues related to your RR com TWC account. We promise to fix the issues in the shortest possible time.