New Comic, Dragon Age: Deception

1. Advisor can be used non-indicative, basically as a way to describe a non-companion character operating in the same capacity as Leliana, Josephine and Cullen. The characters would not necessarily be advisors: they could be handlers, employers and so on. Hence why some posters also phrase it as an advisor-like role. It's more convenient to call it an advisor role because people are familiar with what that entails and so knows what you are talking about. 

Example: let's say the player character is working for Dorian. He would be the one directing players and issuing them missions but without taking to the field himself. He would also be available for conversations unlike NPCs who have limited dialogue and role.  

That's basically what advisors are: non-combat companions.

2. I don't think Calpernia would work as a companion because she'd fall into the same kind of area as Anders if he was a mandatory companion after Dragon Age II. Your character knows what Calpernia has done and is forced to work with her even though to many players, it wouldn't make sense for them to do so. Alternatively, regardless or your character do not know what she has done but the players does and is still force to work with her but without being able to call her out on things like her blatant hypocrisy. Now that I think about, it actually be similar to working for Cerberus in Mass Effect 2 and that was frustrating in quite a lot of ways.

For those reasons, I feel Calpernia would work better as an encounterable NPC. 

3. I think Maevaris would serve better in an advisor role because of her Magister status and power. She might occasionally step into the field but I feel Maevaris' presence as a companion would "break" too many scenarios unless it was limited where she could go.

Example: Why would a bunch of thugs challenge a player character if they are accompanied by a magister? Even if the thugs don't know what's who she is, they know she must be someone of importance and power.

Example: Maevaris would have to be low level which would not make sense for a magister. Solas being weak had an explanation in that it was apparently due to having been asleep for so many and so he had to gradually regain his power over time.   

No, I feel Maevaris would be best as an advisor which would also allow her character to shine without limiting her usage and power. Then when she appears, we would have a real show of a Tevinter magister with all the power and flair that title implies.