That still doesn't really explain how one is supposed to honor the covenant and which actions dishonor it. I would assume it means being disrespectful or using the spirits for purposes that do not align with that spirit's moral compass, but I'd like to know for sure. 

The phrasing for whether a creature can be called could be taken either way. I call my cat all the time, but it doesn't mean she comes. Why would a spirit bother showing up if it has no intention of helping the person who called them. Also, the way it reads it sounds like almost anyone can call a spirit- you're not actually a summoner unless you can control them. "Summoning" implies that the spirit HAS to show face. "Calling" implies that it doesn't have to if it doesn't want to. (At least that's how I read it...)

I'm honestly hoping that there are more than 8 spirits, since if summoners are just summoning such spirits for their powers, it seems like a lot of unnecessary work when you could just be a sorcerer instead and command the elements yourself. I'm also hoping there are tiers, since if every spirit is at the same level of power, there would be no skill level amidst summoners-- no way to tell a good summoner from a mediocre one (aside from number of spirits one can summon I suppose...)