Have a go

[grubstake]

4. last but not least
5. one in a million

 

[kiwifred]

1,4,5,6,13,15 correct

 

[Manpa]

1..
2 heartbreak, HEARTACHE
3.
4 last, LAST BUT NOT LEAST
5 one million
6 fooling around
7 past history
8 upbeat
9 low end, BOTTOM END
10 brain scrambled, CRAZY
11 file up
12 one pace back one pace forward
13 backward glance
14 love hate divide
15 all things great and small

 

[grubstake]

2. heartbroken

 

[kiwifred]

1..
2 heartbreak, HEARTACHE.......x
3.
4 last, LAST BUT NOT LEAST
5 one million........x
6 fooling around
7 past history......,.,.x
8 upbeat.........x
9 low end, BOTTOM END.........x
10 brain scrambled, CRAZY........x
11 file up.........x
12 one pace back one pace forward..........x
13 backward glance
14 love hate divide.........x
15 all things great and small

 

[kiwifred]

2. heartbroken

yes

 

[kiwifred]

8. musically inclined

 

[kiwifred]

Answers
1. one thing after another
2. broken heart or broken hearted
3. but on second thought
4. last but not least
5. one in a million
6. fooling around
7. history repeats itself
8. musically inclined
9. the beginning of the end
10. scatter brain
11. line up in single file
12. pacing back and forth
13. a backwards glance
14. a thin line between love and hate
15. all things great and small