You can remove the 3 bolts on the flywheel cover and you can see the flywheel and clutch. If it is the dual mass it will be thicker. The ring gear and clutch surface of the flywheel will move separate of each other a little.
The dual mass flywheel has a spring system to absord shock. The springs are in between the clutch face and the ring gear portion.
Don't have to remove the engine to do the flywheel.
If going to a single mass flywheel, yes the clutch would need to be changed. The clutch on the SMF is bigger than the stock one.