I think when 4.01m introduced the new FM system it went from "torque off" to "torque lessened".
To be honest... just turn it on so you don't learn bad habits later.
Generally speaking yes the plane is going to climb and dive slightly or move to the left or right slightly because of engine torque. Using elevator and rudder trim will help lessen those two "problems" to keep the plane flying smoothly.
It's never a case of setting it and being done either. You're always adjusting depending on the speed of the aircraft. Sometimes I even anticipate it... in fact I sometimes don't need to look at the gauges anymore either but that's too many years of playing this simulator
Trust me... work on small adjustments with the elevator trim and rudder trim and things will start to work out nicely. You'll have to learn a slightly different technique (of how much to apply) depending on the aircraft but you'll get it.