StoneCold

I actually thought this was Fluttershy's best episode. Rather than simply focusing on her flaws (i.e. Fluttershy being shy), this episode turned her strength (Kindness) into a weakness. I thought it was really interesting to see the analsyis of her ultimate strength. Kindness may be the best policy, but sometimes being kind isn't the same as being nice.

Perhaps 'nephew' is a loose title. Perhaps he's the son of one of her previous students, and so she refers to him as 'nephew'. As for his name, instead of 'prince' being a title, it is literally Prince Blueblood.

I have a long one: King Sombra was the benevolent ruler of the Crystal Empire, until he was corrupted by the evil spirit Umbra. When Celestia and Luna banished Sombra, Umbra left him and passed onto to Luna, turning her to Nightmare Moon. However, when Nightmare Moon was banished, the spirit couldn't corrupt Celestia, and so moved onto the Tree of Harmony. (The tree was defenseless without the elements of harmony, which the princesses had taken from it.) For 1,000 years, Umbra lingered, slowly seeping into the everfree forest. Without the Tree's protection, monsters began to swarm into the once peaceful forest.(This explains why the forest became so dangerous, and why so many dangers seem to come out of it throughout the series) However, when the elements were returned to the tree of Harmony, it was able to banish Umbra, and began to cleanse the forest of its presense. (This explains why the Mane Six made several uneventful trips to the Castle of the Two Sisters without incident, even though the everfree forest is apparently so dangerous) I use this to rationalize why the Castle of the Two Sisters was built in the heart of Everfree Forest. After all, I don't think the princess would want their castle in such a dangerous area.

I thought Inspiration Manifestation was hysterical, if only for Owlicious's reactions to Spike

Applejack Seriously though, Aunt Orange, in part because I'm curious about her story. (An orange when everyone else we've seen in her family is into apples)

Because he was a popular character Well, Discord escaped from his stone prison once, so what's to stop him from escaping again? Maybe Celestia wants to change Discord, rather than having to deal with him every thousand years or so. Either that, or she feared Tirek returning, and wanted Discord on her side.

Tirek suffers because, while he may become more threatening as he absorbs magic, he also becomes less scary. This is because of the rule "never show the monster". The human imagination will usually create a more terrifying creature than what can be shown, so when Tirek's hood comes off, he stops being scary.