I think I see what you are talking about on the carrier. Basically you have a couple options, buy a new banshee carrier or go ahead and replace the bearings and see how it holds up. I can't tell exactly how far it's shaved in but it might still hold the bearing in there just fine, not sure. If it were me I would just get a new carrier, you can probably find them on Ebay pretty cheap and you might even find one that comes with the bearings and spacer. I wouldn't try to make a spacer, you might be asking for trouble by doing that.
As far as the leak, it really depends on where it's coming from. Is it coming from where the shift shaft enters the case on the left side? Or somewhere else?