In the app go to Devices / Edit / Edit on the device you wish to change its behaviour / Power Settings / Power State. There are 4 options, I think the one you want is “Always on, unless the Off key is pressed” but never used it personally I prefer equipment that's not in use to be Off.

I can't remember where and can't look as moving house and X1 is packed away but somewhere there is an option so when switching Activities you can chose to leave existing equipment On or it turns Off.

Consumer Electronics Control. It is supposed to help integration between equipment so when say you turn on your streaming box the TV turns on and switches to the correct input automatically. Different companies can call it different things, Panasonic call it Viera Link. When it comes to the X1 what happens is the Activity turns on the streaming box which using CEC turns on the TV then as part of the Activity the X1 tries to turn the TV on but this actually turns it off as its already on.

You need to use “Electrical Cleaner” its nonconductive other cleaners may do exactly what you say. I did a quick squirt, using the straw it came with, down the gap then turned the wheel.

This can be easily fixed with a quick squirt of Electrical Contact Cleaner. Mine works perfectly again.

To help with your last point as you sound like you are now out of warranty. Get a spray can of Electrical Cleaner and a QUICK squirt using the straw will have it up and running again. And if you still have the old one you will now have two.

Sounds similar to another issue I just commented on. If the Epson instructions are before the Sony move the Sony ones to before the Epson, if it now works look for errors in the Epson instructions. Sadly If an Activity fails part way through it doesn't tell you.

Had the same thing, too long ago to remember it exactly. The difference is a Device is a single item an Activity is a set of instructions that control multiple Devices and runs in order. The problem is that if one instruction is not programmed properly the activity just stops with no warning to say it's failed. To test this move all the Onkyo instructions to the beginning of the Activity and if it now turns on the error is in the Device that was before it.

If the only issue with using the XW6000ES codes is the power button then this is user error as there is no Power Button on the remote. The Off button on the remote turns off an entire Activity and has no function on individual devices. If you really need an off button for an individual device you need to program one of the buttons below the screen on the remote to do it or add it to favourites. Or if you are not going to use Activities buy the U1 or U2.

@dvdmd1. Please explain what you mean by "fix". What is yours doing or not doing? My Apple TV 4K long press of the ok button works exactly the same as the original remote.