Regarding Wolverine Hall, is there a reason why there is no legion garrison there? It seems odd there isn't at least a knight stationed there, or anything related to the legion, or any jail cells. Is there anything specifically mentioned? Or is it more or less because of game mechanics?

More like more or less becuase having a town of Talvanni already being pissed that there is an Imperial presence right on their doorstep doesn't need any icing.

I think its more of an Imperial Guild hall, as well as having the Imperial Cult there.

At the same time, it seems strange that it allows someone to get into Sadrith Mora through a back door, either by Divine Intervention or by the Guild Guide. But then again, the Telvanni don't actually do anything if you don't get those stupid hospitality papers.

I'm also curious about Hrundi and the Fighter's Guild there, are they effectively in charge of Wolverine hall? Hrundi admits that the legion will use the fighter's guild in areas the legion doesn't want to commit to, and the fighter guild hall contains the evidence chest.

It's a way of having an imperial presence without making said presence so forward that it is felt by the nearby, touchy, telvanni, and therefore no need for fear of retaliation. The FG is an imperial institution, although not directly connected to the empire. It's kinda' like hiring a PMC to do a country's dirty work instead of sending their military. That way no one can truly say, without a shadow of a doubt, that it was this country that was responsible. Pretty smart move, IMHO.

^ What he said. Those blood Telvanni need to get over themselves -_-