Yes, "manager-in-training" should be hyphenated. The hyphen helps clarify that the phrase functions as a single modifier describing someone who is in the process of becoming a manager. Without the hyphen, the meaning could be less clear.
Historically a hyphen was used. In modern times 'cross training' is now presented as two words.
Self-made should be hyphenated.
Pre construction - two words not hyphenated.
It should be hyphenated when it's used as an adjective.
self conscious
No.
Underdeveloped should be written as one word, not two words or hyphenated. I hope this answered your question. :)
roller skates
yes
it should be hyphenated: close-out
Roller-skate, as a verb, should be hyphenated. Roller skate, as a noun, is not.
No, "by and large" should not be hyphenated. It is an idiomatic expression meaning "generally" or "for the most part." When using it in writing, it should appear as two separate words.