The correct syntactic usage of "Only"

Question #1: Which of the following sentences has the correct syntactic usage of the word "only"?

Question #2: What do the remaining sentences mean?

Examples:

1. Only I gave him $1.
2. I only gave him $1.
3. I gave only him $1.
4. I gave him only $1.
5. I gave him $1 only.

I believe all five are syntactically correct (under my own personal command of the English language).

1. Only I gave him $1. I was the only person to give him $1.
   This might suggest that there was a situation in which others might have also given $1, but didn't.

   "He was begging for a dollar to use in the vending machine, but people passed him by. Only I gave him $1."

2. I only gave him $1. I gave him money, but only $1.
   It probably implies that $1 is not that much to give.

   "He was two dollars short of the soda. I only gave him $1."

3. I gave only him $1. He was the only person to whom I gave $1.
   It might imply that I could have given $1 to others as well, but didn't.

   "There were beggars up and down the street, but I gave only him $1."

4. I gave him only $1. I would consider this identical and interchangeable with 'I only gave him $1', though I think this is the less common choice.

5. I gave him $1 only. Identical in meaning to ‘I only gave him $1', with extra emphasis on the 'only’.

   "You accuse me of giving him $5, but I gave him $1 only!"

According to the analysis in McCawley's The Syntactic Phenomena of English (starting around p. 68), "only" modifies a following constituent (other than S) which contains its focus. (The word "only" has other uses, as well.) The focus is the constituent which is contrasted with other possible items in the scope of the "only". The focus can be singled out by strong stress in the pronunciation.

In this example, assuming the sentence structure

[NP I] [V' [V gave] [NP him] [NP one dollar] ]

McCawley's rule gives the following results:

1. Only I gave him $1.  focus is "I"
2. I only gave him $1.  focus is "gave" or "him" or "1" or "$"
3. I gave only him $1.  focus is "him"
4. I gave him only $1.  focus is "1" or "$"
5. I gave him $1 only.  (case of post-nominal modifier not covered)

For 2. above, "only" could either modify just the verb "gave" or the entire V', and when it modifies the V', its focus could be any constituent in the V' -- that's why there are so many alternative readings. Similarly for 5, if "only" modifies the whole following NP, its focus could be on either constituent inside that NP.

Multi-word constituents can also be focuses in McCawley's analysis, but in this example I have neglected this possibility.