Sorry I cannot post you a reference as my 200ADV manuals are long gone.
Question 1
It is to counteract Mach Tuck in case you diconnect the AP at speed and altitude so the aircraft is in trim, that is why it is called Mach TRIM?
Question 2 and 3
Which APU model is fitted?
Question 4
Our B732 ADV had one only on the RH MLG