26A is indeed a synonym for opinions
9A - 4 letter synonym for turn which is then reversed, defn last 3 words of clue
1D - 4 letter synonym of "class" having its heart fluttered, defn first two words
I know that 4,28; 20,29; 25; 15, and 30 are five of an exclusive group.
Interestingly Only Connect had this as a question this week, but they thought there were seven in the group, not five....open to interpretation.
You need 7d's interpretation of each word in 24d in order to create a part of the theme aspect of the puzzle to which 25a is connected. (I hope that's not too convoluted to be helpful.)
I am completely stuck with the top half - if I have it vaguely right, there are 2 themes running through this crossword, one literature- based and one song based. Am I correct?
I have all the possible clue letters for 14 down - I can only think of one thing which I thought was a phrase but in fact can't seem to find a reference to it anywhere...