Yes, "over the rainbow" is a prepositional phrase.
Yes, "over the rainbow" is a prepositional phrase.
no
be mine or be in me
By eating skittles apparently.
yes
Am I to Sweet for you?
An idiom is a phrase that makes no sense unless you know the definition. Could there be "somewhere over the rainbow?" Yes, you could have a place that was beyond or over a rainbow, so this is not an idiom. The song is talking about a place that Dorothy thinks is better than where she is now, that she thinks might be beyond the rainbow she sees.
chair talkin
As you know, you can never "catch" a rainbow. If someone is chasing rainbows he/she is going after something he/she can never achieve.
This phrase is from a poem by William Wordsworth. The phrase "My heart leaps up when I behold a rainbow in the sky: So was it when my life began. The Child is father of the Man".
No, blow and rainbow do not rhyme. Here are some words that do rhyme with blow: foe go low mow no row so sew stow slow snow tow To get a rhyme for rainbow, you might have to go with a phrase. Something like "main foe" might work.