1. What do you think Glozelle meant by " it was we who first put him on the throne" ?
We know that Miraz rose to power through shady means, not the least of this murdering his own brother for the throne. It's very likely he had help doing so - likely, Glozelle and Sopespian. I wouldn't be surprised if one or both of them did the deed themselves. Even if that's not the case, they may have supported him when he was climbing the ranks, and now feel he has abused that support.

2. Compare and contrasts Miraz's war council in this chapter with Caspian's in the last.
I find it interesting that, with Caspian, he had dissenters, but at least they were honest - Nikabrik spoke his mind freely, and was allowed to until he started delving into treachery. Meanwhile, Glozelle and Sopespian were very careful to only agree with the king and say things very politely, eloquently - and not mean a word of it, as the whole point was to manipulate him. Miraz responded by making a very foolish decision in a fury, whereas Caspian kept his cool and considered his options... at least, until Nikabrik turned everything on its head.

3. What do you think of Peter's choice of marshals?
Well, Glenstorm and Wimbleweather are rather obvious - they were chosen for their intimidation factor, and Glenstorm is a wise creature and can be trusted to be a Marshal. I find it interesting that Peter would rather honor the traditions of Old Narnia than continue this line of thought when it comes to the Bulgy Bear - rather than find an equally intimidating third marshal, he chooses the bear. It's a good reminder that Peter remembers what really makes him High King of Narnia. I've always wondered whether Peter not choosing Reepicheep was strictly for the reasons he told him, or if that was a diplomatic way of saying (or rather, avoiding saying) the same reasons why he chose not to use Reepicheep as a herald: they all know Reepicheep is an accomplished fighter and the pinnacle of honor, but he doesn't appear as such to the Telmarines at first glance.

One thing I noticed about this chapter was at the beginning, Peter tells Caspian and the others that Aslan and the Queens are nearby, but they're doing somethign else - he's not sure what, but he has faith that Aslan is making the arrangements for their ultimate triumph. One factor of his plan is that, even if he fails to even get Miraz to accept the terms, it will buy Aslan more time. I think it's a pretty clear sign that Peter has taken the lessons from wandering the woods to heart!

1. What do you think Glozelle meant by " it was we who first put him on the throne" ?
I assume they were among the supporters that begged him to take the throne. It is quite possible they helped get rid of the Lord who would have supported Caspian.
2. Compare and contrasts Miraz's war council in this chapter with Caspian's in the last.
Both councils involve treachery; however, Miraz doesn't figure it out and Caspian does. Caspian's council is more above board, things are stated clearly. At Miraz's council, Glozelle and Sopespian work through trickery and manipulation. Tempers are lost at both councils.
3. What do you think of Peter's choice of marshals?
I don't see how the choice of the bear could have been avoided and Glenstorm is an excellent choice. I'm not sure the giant was the best choice since he has trouble following things going on at his feet.

1. What do you think Glozelle meant by "it was we who first put him on the throne"?
Dictators/usurpers rarely comes to power entirely on their own. They usually have a group of strongmen surrounding them, ones willing to do the dirty work. Of course, there are these little benefits and perks that go along with that job, and Glozelle evidently didn't feel that he had gotten enough of them. I seriously doubt that he had enjoyed no advantages related to his position. That's one of the disadvantages of being a dictator: the people you have to work with.

2. Compare and contrasts Miraz's war council in this chapter with Caspian's in the last.
Miraz had a small, a very small, council, even smaller than the How council. Rather surprising, as it seems unlikely that that was a typical gathering of military minds. Where were the others? If there had been more members to take counsel, perhaps Miraz wouldn't have been stampeded into a faulty decision. Of course, he was easily manipulated, because his own pride and a constant diet of flattery had blinded him.

Caspian at least knew that he was inexperienced and needed wise counsel. He had the advantage of wanting to do the right thing, so he was not swayed by false plans, unlike Miraz.

3. What do you think of Peter's choice of marshals?
Quite logical. He was familiar with the protocols of combat (and the language, as well), having had many opportunities to practice during his reign in Narnia. He didn't try to overrule the customs, even if the Bulgy Bear did look ridiculous.