The prevailing spelling is the hyphenated "off-site" (off premises) although this may change over time.
Yes, campsite (a camp location) is one word, also used hyphenated as camp-site.
Both "off-site" and "offsite" are correct. The hyphenated version, "off-site," is more commonly used in formal writing styles to clarify that the two words are connected. However, "offsite" is also acceptable in less formal contexts.
No, "off guard" is typically not hyphenated when used as an adjective before a noun, but it can be hyphenated when used as a compound modifier. For example: "She caught him off guard" vs. "He was caught off-guard."
No, "sign off" is not hyphenated when used as a verb. However, it can be hyphenated when used as a noun (e.g., "She gave her sign-off on the project").
According to MW Dictionary, off-ramp is, indeed, hyphenated.
Hyphenated is preferred- to minimize confusion. an off-work accident, for example.
The term on-site is a hyphenated compound when it functions as an adjective or as an adverb, e.g. "The team conducted on-site visits" and "The team conducted its review on-site."
No, but it is sometimes hyphenated. Take off is a phrasal verb and is always written as two words.
It is not hyphenated.
off-site
Both off-site and off site are correct in different circumstances. E.g. "I am taking the car off site." "Fred's not here because he's an off-site worker"