If they get sore it may be that you can't use the teflon ones for the 72 hours, try replacing slightly earlier.. See how you get on, some pumpers find they need to do this even with the metal ones!
The metal insert that you pull out from the teflon ones we call in our house 'hat pins' :lol:
If reducing the amount of time between changes doesn't work or changing to the steel version, try another manufacturer who has the same fitting/lock system as your infusions sets as it may be something to do with the manfacturering lubricant being used..
As to other parts of your body you can use you can insert a the infusion set anywhere you have an fat layer, so all the same sites on arms, legs buttocks and I heard of pumpers to use their breasts/chests to insert there infusion sets..
But remember though if you change area's ensure that you do extra BG checks as sometimes differennt area's can have different adsorbtion rates..