First, the "stonger", "weaker", or "Average" rating. Basically, the advisor does knwo what the combined hit point total is for you army and the other Civ. It's semi accurate infomration that is available to all the Civs. When other Civs are Stonger than you, they are more likely to attack. OK, when are you stonger.... when your combat strength (combination of defense, attack, and bombard) is 25% greater. So, simply put if I have 20 warriors and the AI has 15, I will be stronger than they are. If the AI has 25, I will be weaker than they are. Otherwise, we are Average.

One key thing here is that combat strength is used, which means upgrading all units can have an impact on this rating. Think about this way, a Rifleman is the defensive opposite of a Calvary (1 point difference). And fortified he would stop at least 1 Cavalry and generally 2 or 3. But 1 Infanry is almost equal to double the Calvary. Now, with that comparison, think about how many Infantry (defensive units) you have versus offensive units (at least until late in the game). The key is a strong defense to keep this rating favorable.
 

Second item, under the MA, I assume you mean under the other Civ you are viewing. I am not sure why thay give you a "city" view. I can't seem to ever ger any information there, so it's almost like it should be disabled. But if you plant a spy in the other Civ, you will then get the unit view which would allow you to see how many of each unit they have. I have to say that I don't use this often becuase of cost, but I can see a benifit to knowing what you are really going against. Especially when you are not sure if you are going to win the war.
 

I think that there is a way to see where every unit is of an enemy under one of the spy options. That's beyond just the units, which all you need to do is have a spy planted in the other civ. The spy option I think is something like steal plans, but I've never done it because it is costly (2,000+).