^ not sure about the different sizes of threaded areas. As for the original bearing set, in theory loose ball bearings are better than ones set in a cage because you will be able to fit more of them and so it will be stronger. It's very easy (and cheap) to get new ball bearings. Just take one along to make sure you get the right size. Wipe clean the bearing slots, pack with grease and push the new ball bearings into the grease to hold them in place. Cheap and you don't have to pay someone with a headset-press to fit a new one.
^ not sure about the different sizes of threaded areas. As for the original bearing set, in theory loose ball bearings are better than ones set in a cage because you will be able to fit more of them and so it will be stronger. It's very easy (and cheap) to get new ball bearings. Just take one along to make sure you get the right size. Wipe clean the bearing slots, pack with grease and push the new ball bearings into the grease to hold them in place. Cheap and you don't have to pay someone with a headset-press to fit a new one.