Anyone else have this happen?
I did have an issue when I accidently hit Farkas during a quest, he would constantly follow me and engage me in conversation in an attack position. I think the way I fixed this was commit a minor crime, paid the fine It seemed to fix the problem.
As for the ebony blade Since I was finished with the companions questline I have no Idea if it has any effect on Vlkas at all ( while holding the ebony blade anyway).
As for leaving Jarrvaskor and having the game freeze when leaving that yes it happened to me a few times. That's why I have 4 constantly rotating saves , never more than an hour or two apart.
If Farkas is following you and engaging you in conversation, it is most likely due to having a bounty in one or more holds. Clearing any bounty you have will likely solve that problem. I've never heard of Farkas having any problems with you carrying the Ebony Blade either.
As far as the freezing goes, it is good that you keep enough saves. If you are getting a lot of frequent freezes it sometimes helps to clear the Xbox system cache and less frequently the game cache.