But to suggest that Loghain had absolutely nothing to do with the massacre of the Couslands is...a stretch.
Not really.
The timing of the event with Ostagar and Loghain's alliance with Howe makes this extremely fortuitous for Loghain. In fact, it's far too fortuitous for several reasons and additionally considering that Loghain was preparing for a "confrontation" with Cailan concerning his desire for an alliance with Orlais. According to Gaider, the poisoning of Eamon was done in preparation for this confrontation so that Cailan would enter the situation having "already lost."
Bah, I reject the poisoning of Eamon being done before Ostagar. I've gone over that before.
As for his alliance with Howe, that happened after Ostagar. Howe took advantage of the presence of the Darkspawn in the south to usurp Highever from Bryce, no doubt from a mentality that it rightfully belonged to the Howes -- as the two families had been rivals during the Occupation and, IIRC, longer then that.
Howe then instilled his own men in Highever, naming himself Teyrn, before going to Denerim to answer Vaughn's call for reinforcements to deal with a problematic riot in the Alienage. Using the chaos there, he took Vaughn out of the equation, imprisoned him, and said he was one more death from the riot. He then named himself Arl of Denerim as well.
When Loghain came to the Landsmeet to get the Bannorn to rally under him, and they refused because they were shortsighted fools, Loghain found it necessary to seek a political aide. Seeing the amount of terrain he commanded, he picked Howe. Howe's lands that he had now stolen were crucial to maintaining the military advantage, and Loghain had to allow Howe to keep them for the moment so as to not risk antagonizing him. If he had been antagonized, a potential third front would've been waged.
Yet, if we assume that Loghain had nothing to do with the massacre, then that means that he didn't have a plan for when the only other teryn in the nation decided to back the king
Look at it from this way.
If Cailan had proved amenable to wisdom, there would've been no confrontation except regarding the Celene issue (if that popped up)/Orlesian reinforcements, which Loghain didn't know about. Had that popped up, I doubt that even Bryce would've supported the king. Bryce is no fool. He's a smart guy. He would've seen the issues this would represent, despite how he and his wife have traveled to Orlais -- no doubt as diplomatic agents to instill peace.
Peace is one thing. Handing the nation over to the Orlesians again in a bloodless coup is another matter.
If Cailan had proved amenable to wisdom, then they all would've been on equal footing. Remember, he was supposed to be at Ostagar himself. Barring some mishap that resulted in his death there, they'd probably be on equal ground.
And had Cailan died, Bryce would've seen firsthand how hopeless the situation was and, without knowing of Alistair (of his existence/if he was even alive) he probably would've backed Loghain. He's an ardent royalist, but that doesn't extend very well if no heir is in sight.
1) Bryce Cousland was a loyalist to the crown
Though he had his own doubts about whether or not the darkspawn invasion was a blight, he still obeyed the king's orders and rebuked Howe for speaking ill of the king. His family also never bowed to the Orlesians during the rebellion and fought to restore Ferelden's freedom and rightful heir to the stolen throne.
Bryce respected the king and held duty to the country as necessary for a lawful citizen. Without substantial proof to back Loghain's suspicions (Which loghain himself could never find until long after Cailan was dead), Bryce would see no reason to betray or stand against the king. Opposed by the only other teryn in the country, Loghain's attempt to curtail Cailan would be in danger.
As Corker pointed out, being a loyalist doesn't mean being a sycophant.
2) Bryce Cousland was well-beloved and regarded by the bannorn
Not only is Bryce a war-hero; Not only is the head of one of the most powerful houses in Ferelden; But he was so well-loved by the bannorn that many actually preferred for him to be king rather than Cailan. This sounds like an individual who had more political clout than Eamon or Loghain combined.
If Loghain was actually going confront Cailan, he would also need to have the bannorn supporting him. A prospect made far more difficult is Bryce Cousland opposed Loghain. When one Teryn argues against another Teryn, who do the lesser lords support? The one that they trust or the one who pays them and I could see Bryce beating out Loghain on both scores though he'd only need the former.
Eliminating Bryce and his family also means eliminating your most powerful potential opponent. It means that when Loghain confronts Cailan, the bannorn may not back their king so readily.
Loghain doesn't have much political clout to begin with.
Also, what Corker said again (I have a feeling I'll say that for the next few things as well)
Loghain was adamant for keeping his daughter as ruling queen of Ferelden. So much so, that he even rejects Maric's bastard son on the grounds that he'd be a puppet for Eamon (valid concern, but hypocritical coming from Loghain's mouth).
Also not really. It's not hypocritical at all. Anora backed him as Regent by not denying it, and he's not using her to further his own agendas by having her be the rubber stamp. He's the one calling the shots at the moment, because at the moment they're in a war and he's the best poised to deal with the combat aspects. The problem arises from the person calling the political shots, which is Howe. He's the one manipulating Loghain, no doubt saying that Anora's unfit to rule at this time because her mind is clouded from Cailan's death, so that Loghain won't turn to Anora for aid.
Think Grima Wormtongue.
Actually, I think we do. There's some ambient conversation between Howe's troops in the kitchen when you go to Rescue the Queen. I don't recall the exact wording, but Highever was not a happy place, and they were glad to be away from it. They were hated, although I don't know if there was violent resistance.
I believe there was a rumor that said as much re: violent resistance. You're right that the people there hated Howe's men.