The bearing you see in the middle of the flywheel is the spiggot bearing, it has to be there on any RWG 4AG. You can get replacement ones from repco for a handful of coins. They are exactly the same as the 4AC ones, so just ask for one of them. These can be a nightmare to get out sometimes.
The metal on metal sound could be the thrust brace? (The bearing attached to the fork, which pushes the clutch in). Spin it by hand to see if its worn out or not! Again you can get new ones from Repco etc.
Andrew.