[Zero10]

The races should have no grooves with so little time on them.
When you put the inner/outer races together, the slots are angles opposite ways. It only makes sense once you have seen it. It goes together quite easily the other way, but it is as good as locked up. I see you figured that out.
If the races are good and the joint was repacked with grease I would run it until it fails. No point in cutting it's life short by replacing it now, especially not after all that hard work!

As for the loctite question......
If you are re-using the bolts, then I would use blue loctite on the threads. If you are using new bolts then use nothing. Of course make sure that the mating surfaces (the face of the outer race and the stub axle/output stub of the transmission) are absolutely clean and dry, because that is where all of the power transfer takes place.
My rule is to only use the bolts once, but if I absolutely must re-use them then I do apply blue loctite. I've had the bolts back out before so I am rather paranoid about this.