Good Riddles

Question: A man wants to have a party in thirty-one days where he will be serving his 1000 barrels of wine. The only problem is that one of his enemies poisoned one of the barrels. The poison kills any man who drinks any of the wine in about 30 days, give or take a few hours. The man has 10 plants that are also killed by the poison in 30 days and can be used to test the wine. How can identify the single poisoned barrel of wine?

Question: First think of a person who lives in disguise,
who deals in secrets and tells naught but lies.
Next tell me what is always the last thing to mend,
the middle of middle the end of the end?
And finally give me a sound often heard during the search of a hard-to-find word.
Now string them together and answer me this,
which creature would you be unwilling to kiss?

Question: I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter.

What am I?

Question: What single line can you add to the following statement to make it true?

5+5+5=550

Question: With one you can't count past six,
nor can the gap between v and x be fixed.
You can read all of these lines,
but can't say what solves me.

What am I?