a) I think it's a positive song as i can notice some verses that have the meaning of a positive feeling, such as " I never knew how proud i would feel / Just standing in the rain"
b) Yes, as some verses refer to the sweat and weak knees, such as " Sweat drips down my spine/ And my knees are weak"
c) I guess the singer feels good as the text refers to someone who can make u feel more confident and encourage you not to give up at hard points.
d) The words which tell me the song is about Scotland are those which present the colors of the national flag " blue and white "