c) The Arduino is widely touted as a means for ordinary folk to interface hardware and software with relative ease. On this forum I'm often advised to take precautions (zener diodes, oscilloscopes, negative voltages etc) that feel out of my reach. It feels a bit like false advertising - but then I know it isn't and you guys just know so much more than the people on the web and on make.com pushing out these tempting write-ups.
I hope you don't think less of me.
The thing is that the Arduino is in my opinion the easiest microcontroller platform for beginners to do all kinds of fun and/or useful things. So many software library and sketches avalible, lots of projects documented and posted, etc. However there is nothing fool proof about the basic electrical properties of the AVR controller chip, applying reverse polarity signals or voltages above +5.5vdc can instantly destroy the chip. So much is dependent on a beginners knowledge of basic electronics, and if little or no experience is apparent many of us will try and stress all the bad evil things that can happen and what one should do to try and avoid those problems.
So in your example of wiring the speaker alarm output directly to an arduino analog input pin one would ask how do you know that you will wire it with the proper polarity so as to not damage the input pin. How would one know if the voltage level of the signal is more then 5.5vdc or not? That doesn't even address what kind of signal it is for proper software recognition of the signal.
So yes we sometime may come across as overly picky about wanting details before trying to give beginners possible solutions, but it's based on hearing lots of new comers with damaged boards asking for help and advice after it's a little to late to help, as the damage has already happened. 
Lefty