Just don't over-tighten it .. I've seen a picture of a block where it didn't go well!
Quite.
A dab of Loctite is all that's needed to seal it.
I'm guessing to clean it off first? Does oil get into contact with the sensor at all? It sits fairly middle in the block hence the question about draining it first and cleaning the plug and thread inside.
Yeah, best to clean the sender and the thread in the block, I use paint thinners for that and then avoid touching it following cleaning. It will still need to be done up firm, but not tight. That it is screwing in to an Oilway thread tape or anything like that should never be used.\, you don't want any of that ending up in there !!
Also, with the standard switch, that Earths via this thread for it's electrical operation, if thread tape is used, then it's not likely to be able to Earth. I have never had any success with thread tapes on Oil in any case.
The Oil Level when the engine is off, is well below this sender and it is pumped oil when it's there, so with the engine off, there's no oil that will pour out when the switch is removed, though I would strongly advise cleaning the area around it before removing the old one.