Power for these events is easy, but a totally different animal.
My experience is many festivals / concerts. I have done mainly large events 40,000 plus people nine stages and 60 plus vendors. The simplest way to provide power is with generators. Power poles for short duration events are not worth the effort. ROI on power pole is achieved when event is a week or more.
Permit process here in CA when we use generator is just a life safety inspection grounding and trip hazards. I have the promoter or event organizer handle any permit or inspection fees.
If you are interested in doing this you can make money if you have the right gear.
Check out
http://www.tmb.com/products/ProPower/
It is basically running a bunch of extension cords when you break it down to what it is you are really doing.
Carnivals rides are basically a bunch of large 3phase loads. You can provide for these with a properly sized generator or X number of generators and then distribute power with CAM cable. (CAM lock connectors on large welding cable)
Carnival booths and vendors are small single phase loads, except food vendors can be 50amp 220, you can use spider boxes and 6/4 for the small loads
Fairs same as Carnivals with usually the addition of stages.
Staging power usually requires you to just provide 3h to the staging sub contractor who will usually handle powering their equipment.
Concerts basically large 150 to 300 KVA per stage for big concerts, 25KVA and up for smaller stages. Things to remember, power going out equals very bad things for you. I parallel two generators so if one goes down there is not a problem. Also lighting and sound power should be separate, lighting is a lot of non linier loads and HID so sound guys prefer a clean separate source, just remember to bond your grounds at the gens set together to avoid ground potential differences on stage.
The people who are currently doing this work are not electrical and are not required to be electricians, unless it is a union facility and even then they are in a separate union and not actual electrical contractors. You can market your superior knowledge and qualifications and get jobs and usually more money.
Important things to keep in mind.
-Every run has a properly sized breaker; do not use fuses trying to replace fuses during an event very bad
-every 120volt circuit has a GFCI no exceptions, I also use
http://www.bender.org/ on my sub feeder runs when they will be in public areas or when fencing will cross over my cables.
-Every power source is properly grounded, plan on placing generators near dirt so you can easily drive rods, also plan on leaving the rod, way easer to pound it in a few more inches than pull out 8 to 10 feet
-All cords in traffic paths human and vehicles need covered to prevent damage and tripping, also remember you will need to comply with ADA rules
http://www.yjams.com/
Fuel for generators I use only Diesel gen set and use BIO-Fuel no problems with spills and makes tree huggers happy
If you have any further questions I have over 10 years doing event power as a weekend hobby.