No.
Yes, "low-to-intermediate" should be hyphenated when used as a compound modifier before a noun.
No, "two thirds" should not be hyphenated. It is a compound adjective that functions as a single unit modifying a noun.
Yes, "hard worker" should be hyphenated when used as an adjective before a noun, as in "She is a hard-worker."
Several sources now list the compound (gerund) form without the hyphen (perhaps the evolving use of previously improper language). However, as an adjective it is still usually hyphenated for clarity. NOTE : Spell Check does not agree. Example: "His decision making was criticized in the press." Example: "The legislators examined the mayor's decision-making authority."
Yes. Compound adjectives are hyphenated in English (unless they are already percived as one word, like "lukewarm").
The saying "thank you" is an expression of gratitude. It can be hyphenated to form a noun or adjective-"thank-you", denoting a message, utterance, note, letter, gift, etc, expressing gratitude. Source: http://en.wikipedia.org/wiki/Thank_You So, here's an example: "Thank you for sending me that thank-you card in the mail."
The hyphenated plural spelling "thank-yous" is usually recommended.
Yes, it should be hyphenated.
Yes it should be hyphenated.
A business thank you note should be sincere and formal and is common after an interview. Today, a thank you email is more common and should be formal and contain a summary of what an individual can bring to a company.
Yes it should be hyphenated.
yes check-up should be hyphenated
It should be hyphenated.
You can if you like, but keep it brief. Dear Mr. So and So, I was happy to be of assistance. And signature. We don't want this to turn into an epic.
If you really want to but it would be rather silly. Would you then expect the recipient of your thank you note for their thank you note to write a thank you note for that too?
"Field" is not hyphenated.
Yes it should be hyphenated.