First of all, if you sell single seats to the public, rather than the whole capacity of the aircraft on a "sole use" charter basis, you will either need a full Air Transport Licence, or an exemption (pleasure flying is a special case). It also needs to be done in your own right; you can't do it on the back of someone else, as you can with an AOC sometimes. Again, there is a special form to fill in which will cut out most of the lack of communication over this subject, and you should find a copy in Ops.
Secondly, you will need to arrange arrival and departure slots, which are usually at a premium. Because of the numbers of aircraft involved (usually over 126 H1 types alone at the Grand Prix), there will be a briefing for all concerned well before the event, at which all companies are expected to send a representative. At the very least a Notam will be issued. H1 helicopters, by the way, are less than 15m long, and H2s between 15-24m; they therefore require different treatment at their feeder sites.
A feeder site is one where more than five movements take place in any one day in connection with an event, as a result of which they require special facilities (a movement is a takeoff or a landing). If using H1s you can get away with normal equipment as used for pleasure flying, but H2s need something a bit more macho. Actually, it's basically the same, but the vehicle must have four-wheel drive and there must be a minimum of 60 gallons of water and 5 gallons of foam concentrate, with equipment able to deliver it at 40 gallons per minute. A minimum of 100 lbs of CO2 or 50 lbs of dry powder or BCF is also required.
The rescue and medical equipment requirements are also more comprehensive, needing transfusion and resuscitator gear to be readily available in addition to:
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large non-wedging axe

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small non-wedging axe

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grab or salving hook

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1" cold chisel

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4lb hammer

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fire resisting blanket

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heavy duty hacksaw with 6
spare blades

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suitably large ladder

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feet of 2" line

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1 pair 7" side cutting pliers

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24" saw

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large slotted screwdriver

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large Philips screwdriver

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1 pair tin snippers

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pneumatic rescue chisel with spare cylinder

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Chisel and retaining spring

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quick release knife with a sheath

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enough pairs of flame resistant gloves

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24" bolt cropper

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3' 6" crowbar

Line Patrol
It's pretty hard to get lost doing this! You will be carrying observers from the Electricity Boards, under their normal procedures, which are pretty exhaustive. All their staff are fully and professionally trained to exacting standards - they need to be, as following and inspecting tower lines calls for a high degree of proficiency and concentration from everyone. The very nature of the exercise (flying close to the lines inspected) means that for most of the time you will be very near the avoid area of the Height/Velocity envelope. In fact, you will be flying at such a speed (around 50 kts) that, if the engine fails, you will be going nowhere but down, which is quite interesting when the line runs through trees and you have to decide whether you're better off in them or dodging the cables.