1) Power buttons on roku remotes have always been for turning TVs on and off – not Rokus. Historically, Rokus have not turned off, but they recently added a “low power mode” which happens after a period of inactivity. Some people find it confusing and turn it off. A button such as home will wake it from its sleep. Power will not since power is only for the TV. (I can see how that could confuse noobies.)
3) Roku doesn’t claim (and I think actively disclaims) supporting sound bars and AVRs. Although sometimes it ends up working via the remote controlling the TV and the TV sending CEC commands to the sound device. HDMI-CEC has to be enabled/supported on both devices for that to work. Your Dish remote controls the sound bar directly with IR. Likewise, my Dish remote supports my TV (power button) and my AVR (volume and mute) and I recall programming each separately. Unfortunately, Roku remotes aren’t that versatile.
4) If your device freezes and there’s no pattern (like it only freezes on a specific app), then I would swap It out at the store. It’s been a couple of years since I’ve had a crash and that was on one specific video on an obscure app and you could see that there were lots of decoding problems (glitchy video) even before the crash. Your description of 4, plus 2, makes me think a swap may be best. Then again, on #2, I’m not sure if we have any/many star link customers on this forum yet so there could be “young ISP” issues as well.
5) Is History on Hulu? If so, ask History to include Hulu as one of the options. Possibly they know of the problem and have some other reason – like contracts not allowing it – but it doesn’t hurt to ask.