1) Arena floors are rarely from steel. Logistics are the main reason.

2) No, not all arena's have a pit or any arena hazards.

3) A Whiteboard is a "fun" fight, no set limit on participants. Just write your machines name on the whiteboard, and if the opponents are too dangerous to your taste, you can wipe out.

4) Depends on EO.

5) Some arena's allow OOTA's, others have the sidewall semi flush with the polycarb safety barrier.