In crossroads of twilight, Nicola is mentioned to have foretold the dragon reborn will do nine impossible things. The only three impossible things I see Rand do is cleanse saidin, seal the bore and swap bodies with Moridin. What are the other six?
I think I would just reduce the size of some of the worse plots, have less forsaken coming back after death and either have more Fain or just kill him off after book 4.
I think there is free will. The pattern can nudge things in a certain direction but people can still choose. Mat could have chosen not to help the Tairens and Cairhienin but his sense of duty meant he did.