Hehe, at Bar 28 it's meant to be a french horn, but for some reason, Sibelius spazzed up with the labelling ...
At Bar 33, I mainly doubles the bassoons together so you you actually hear it in the middle of everything else blaring out at the same time, and for the Largo section at Bar 19, I'm kinda surprised you thought it was too longwinded, I'd already shortened (I mean, you should really listen to the Noon Witch by Dvorak, that has a infinitely long section).
At the Maetoso, I was trying to get the epic feel ...didn't care much for any movement, and basically wanted it to sound a little like Dvorak's 9th Symphony 4th Movement but with a little less movement, which is why I opted to go virtually full chords. I'm not too sure though, so I might change that...
Thanks for the feedback!!