if it's anything like the EM1 that I had a similar issue with, you can unscrew the switch from the back of the ignition barrel. No need to tough sheer bolts.
You could disassemble the switch and possibly solder extra contact points that have worn out but I'd buy new for safety sake, I believe it could switch off while driving which isn't good and that's why they were recalled.
If it's getting into the oil you would see excessive white smoke out of the exhaust. you could have a minor leak which is going nowhere or you could have an issue with wet floor carpets and your internal heater matrix is fecked. Don't top up with water, use coolant and check all rad hoses are...
did you replace the rocker cover gasket when you did the chains or keep original, sometimes a bit of gasket sealer is applied near bends or creases in the head/cover. Search the forum as this has been a previous topic of discussion.
there must be something drawing a current from the battery while it's not in use. You need to investigate where that is, it could be your x-carlink or something else.
I'm the same, I've taken the odd spin in an 8th gen, and while I felt it was a bit more comfortable, it wasn't all that better to justify the extra expense and then the 2.0l petrol is a little lacking in character compared to my k20z. I'd ideally like to see the 1.5t in the new Civic Saloon, it...
Have a look at your calipers and make sure they're not binding, the knock you get when you stop and move on again could be caliper related. Same with the notchy steering you're probably feeling the caliper binding a bit more,
Have you ever noticed an change in it, lets say for instance if you've replaced rear pads, does the noise change? Does it get louder or remain the same? Also might be worth taking a look at your rear door hinges, door lock, boot latch, hinges etc.