It depends on where you would prefer to sit. Typically lawn seats are more abundant as many prefer sitting in more premium seats (under awning), however if these more premium seats aren't sold out at time of concert, you may purchase them at the venue. Seating is first come, first serve.
Yes
If you are looking for lawn seats, then yes. They are normally available. If you want an actual seat it will depend on what they haven't sold.
Depends on who the is at the venue and what kind of ticket you are looking for and how many.
Usually
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