Good Riddles

Question: A trail, a union, together tied.
Come across me and you will find,
you cannot change the course I'm on,
without me you cannot travel on.

What am I?

Question: What do you use to hoe a row, slay a foe, and wring with woe?

Question: What room can no one enter?

Question: A man and a woman both carrying baskets with eggs inside passed each other on the sidewalk. The man told the woman, "If you give me one of your eggs I will have twice as many as you, but if I give you an egg you and I will have the same amount."

How many eggs were in each basket?

Question: While you were folding a letter I got you.
Usually you will do whatever it takes to avoid me,
but now you can't help but find me.

What am I?