Ive never seen the bolts leak. The case is sealed around the bolts and they dont go into the fluid either. You sure its trans fluid and not brake fluid from the slave where the line connects to it?
Youd have to split the case if it is trans fluid to fix that.
Ya the races just slip in. The spacer is to set the clearance for the bearings. All the races should have a spacer so dont get them mixed up about where they go. I recommend changing the input and output seals along with the syncros while its a part.