Answer:
My second is performed by my first. A thief by the marks of my whole might be caught. What am I?
By myself, I'm practically nothing. Worthless as a leader, but when I follow a group, their strength increases tenfold. What am I?
I start with T end with T and within me is T.
You have to travel far before you turn it over. What is it?
I need to be taken before you can have me. What am I?
What is always coming but never arrives?