Can someone describe the Roku interface? - TWC TV and Apps

This question is about "Can someone describe the Roku interface?", with Time Warner Cable TV and apps. I've been told that when I switch to Spectrum, DTAs will no longer be available and I need a full set-top box for every TV. This isn't practical for a couple of my TVs - in particular one wall-mounted on the patio. The TW rep I was visiting with suggested Roku as one possible workaround.

How do you get the TW/Spectrum channels entered into the Roku system? The Roku guy tells me I have to manually enter every channel. Not that I really watch 100s of channels, but still...

Is there a channel guide? Can I see what is showing on a particular channel at a given time, possibly in the future?

I don't think I can go directly to a specific channel number like with the set-top box. Is there anything like a "previous channel" button so I can easily flip back and forth?

I'd just like to hear experiences from people who have tried it... reiiability, usability, etc.

This topic covered Can someone describe the Roku interface?, and TWC cable tv service.