Underdeveloped should be written as one word, not two words or hyphenated. I hope this answered your question. :)
Roller-skate, as a verb, should be hyphenated. Roller skate, as a noun, is not.
One word is fine.
Self-made should be hyphenated.
Pre construction - two words not hyphenated.
No, "fourth floor" is not hyphenated. It is written as two separate words.
It should be hyphenated when it's used as an adjective.
self conscious
No.
No, "miles per hour" is not hyphenated. It is written as three separate words.
Roller-skate, as a verb, should be hyphenated. Roller skate, as a noun, is not.
No, "self respect" is not a hyphenated word. It is typically written as two separate words.
roller skates