You might have better luck posting a new question, but I'll give you some info.
Creo Parametric can open native SW parts, but you get a dumb solid. It's a bit smarter than STEP or IGES in that any changes to the SW can be updated in the Creo part. I'm not sure if this is in the foundation package or an add on.
I don't know if Creo will open SW assemblies in the same way.
Drawings are still a problem. The only way to import them is via DWG or DXF, which of course looses all associativity to the part or assy model.
There are some built in feature recognition tools to turn a dumb solid into a feature driven model, but I've not used them to know how well they work.
The most robust solution would be to remodel them in Creo. Depending on your situation, you might want to keep them in SW until you need to make a major change and then remodel them at that time.
Good luck.