When we went over the changes to the law last year I was promised they would not require WCOs to retake the class for recertification unless they added to the class. At this point they have not added to it so if you have taken the WCO class that is all there is.
They have been talking about adding to the class but I think it will consist of additional classes to add to your certification.
Case in point they are currently in the process of putting together a program for WCOs to do bear control work through trapping and bait & shoot. When they have it done they will have classes that current WCOs can take that will allow them to do bear control work. You will still have to have a special permit.
Right now there are a handful of WCOs that are allowed to do this but they have not certified anyone to do this for probably 30+ years. I'm not sure when they last did this but I do know there are very few left and there is demand from small timberland owners.
As for experience to trap what we are allowed to trap now I doubt there will be much thought to that. Truth of the matter they do not have anybody that knows much about trapping. It can be tough to learn the trade. Best would be if you can work for an experienced trapper but many of them are pretty closed mouth because they don't want the competition.
Fur trapping is the usual first step for trappers that become WCOs but it really is apples and oranges. You will learn from your mistakes. Kind of the school of hard knocks.