(2) The manual says not to use use carb heat on approach unless there is evidence of carb icing. This is rather different to a C172 where it's pretty much mandatory. I have 100+hrs on a -161 and never saw signs of carb icing with, or without, the carb heat including right in the middle of the icing curve.
Funny. I transitioned from the 172 to a PA28. 100+ hours in Cessnas and never saw carb ice. I had 4 hours on the PA28 when I got carb ice in 75% power cruise. At 1000 AGL. At night. (This happened just 2 nights ago.)
It took 4 minutes of carb heat and me wondering if we were going to be able to maintain altitude before we recovered full power. By that point, I was already within gliding distance of the airport I had diverted towards.
Don't take it for granted that a Lycoming powered PA28 won't get carb ice.