A few question for hosting a big tourney.
Suppose you as a TO were planning a really big Magic the Gathering tourny, AKA Power 9 big.
-What would be the best way to contact, or get "good" judges to judge your event?
Talk to the Premiere Tournament Organizer in the area (the guy who runs PTQs and PRs). They should be willing and able to help you find a good team, but also give you advice. They are all veteran TOs and used to running events of this scale.
-What would be the correct number of judges?
I would get a recommendation for a Head Judge from the PTO and talk with them about the judge staffing. You will need 1 HJ and most likely around 3 floor judges.
-What would be the correct payment for a judge/judges?(feel free to PM this one)
You could ask all of the judges ahead of time and work out an amount of payment and if the judges want payment in cash, product, or singles. Options make comping a lot easier.
As a player there is also a few questions that need to be addressed.
-What would be the best type of venue?
This is something that you want to ask your PTO about. They'll have experience with the various venues and can help you find a good venue.
-What would be the best source of food/beverages.
Some venues don't allow outside food or drink. If this one does, there's a bunch of things that you can do. You could order a bunch of pizzas and bring a few cases of soda. Put the soda in a cooler of ice and sell that. The PTO might have advice for that. You'll need to bring an extra person or two to help out with food, drink, registration, etc. In general, more staff is better than not enough staff. If nothing else, you can give them a little something, such as free entry to play, if you won't need them.
-What do you look for in a very big event. AKA side events, type 4, winning T-shirts, door prizes, etc.......
At the PTQs around here, we do side drafts. You might consider doing them and/or an 8-man single elim for a Drain or something. Door prizes don't need to be anything spectacular. Just a little something can go a long way. For example, look at Myriad Games and their cookies. It's not a lot, but it's still really cool to get a free cookie to munch on.
-What do you look for in the judging staff?
The judging staff should be able to come in and work together to make the event run as smoothly as possible. In general, when I judge, I have the expectation that I will walk into the venue, greet everyone (the TO, the rest of my team, the players, the admin, and anyone else), get together with the others that I'm working with, find out what needs to get done. And get it done.
The judges should be responsible for running the actual event from signups to scorekeeping to deck checks and walking the floor and handling rules questions or disputes. The TO's job is to get the team together, get the venue, and get the players. They handle prize structure, and any issues that come up (the pizza guy got lost, you need more soda, etc.)
My biggest advice is: talk to the PTO and get a recommendation for answers to your logistics questions. See what they say, and if you have questions as to why they advise you to do something a certain way, ask. Also, make sure to get a recommendation for a HJ and talk with them. Veteran PTOs and veteran HJs should prove to be your biggest advisors when learning how to run an event.