It seems you have a mixture of things going off natural and unnatural.
The cooker and kettle, they could be the fuses going in the electrics.
Computers every now and again do decide to do their own thing, lol even mine sometimes loses it volume until i reboot it again from the beginning.
Radio switching itself off and on, if its the button you can see if being presses in and out or the switch has changed postions on the radio, thats more paranormal. if it just goes off and on with no buttons on it changing positions, its more to do with the electrics in the walls.
The receipts depends on what they are made with. sometimes contact with air and light can make them go darker, hence them being brown on the top, not the bottom.
I suggest you do a recreation experiment to determine this. If you have another reciept from tescos from similar material made from it (some are shiny surfaced, some arnt) then do the same thing again, put them on the bread bin. Especially on a day like today, its nice and sunny and sunlight can destroy pigments sometimes. Then if it hasnt happened again, you know the first time was paranormal.
The radio when you switch it on, make sure you are aware of the positions of the buttons. so if it does go off, you can check the plug wall, buttons on the radio to see if they havent moved. If they have moved to the off postion, you know its paranomal. if they have not moved and its gone off, its circuitry in the walls.
Also if you can get a person to check your electrics, following the wires with a special meter can see if theres any breaks around that needs re-wiring and also can check your fuses.