This may take a while to answer. First, every campaign needs 4 things: a Political Consultant, a Fundraiser, a Press Secretary, and a Campaign Manager.
Political Consultant: Someone the candidate hires for a Presidential campaign specifically. It will be a company with a lot of resources with offices across the country. The firm will usually deal with that particular party (Rep. or Dem.), but not always. However, there will always be one person that will be the contact between the Presidential candidate, his staff and the political consulting firm.
Fundraiser: Sometimes you can have an individual, who will hire people to assist in raising funds, or the political consulting firm will also have a branch that handles the fundraising part of the campaign in addition to their other duties. It is up to the Presidential candidate, I have seen some hire a person because of a prior relationship in past elections, but still had the political consulting firm do most of the work. However, that person traveled and was there to assist the candidate with all fundraising matters on a personal level while the consulting firm handle matters at their office.
Press Secretary: This persons job travels with the candidate and speak on their behalf and meet with the press to present the candidate in the best light. And, to put out fires that might arise during the campaign. They usually will have anywhere from 5-10 people working under them and traveling with them also. Although the handle the press, the political consultant handles all the minor "make sure the candidate name's appears everywhere" press. That includes the Internet and print.
Campaign Manager: I guess you could call this person the ring master to this circus. This person is the major decision maker for the candidate and is the boss of everyone, except the candidate of course. The person is responsible for all departments, including handling all issues related the party which nominate the candidate. No easy task. The individual must hold briefings every day, several times, to stay abreast of all things going on in all areas of the campaign. This person also travels with the candidate a majority of the time. Presidential Managers usually have about 5 people working under him directly (which mean they are in direct contact with him and the candidate), but they will normally have one go to person that is what you might call the Assistant Manager.
There is usually a 5th group which is unspoken, but it is in every campaign around the world and that is the organization that finds out the secrets of the the opposition. Buried, behind lock doors, whatever they are it is their job to find them. Whether they are made public is up to the candidate, not all candidates choose to use this information (I know from personal experience).
How many people work for the Presidential Candidate?
Every state has a Rep. or Dem. State office so that office will automatically set up an office for the Presidential candidate where those people will be working for the candidate. Whether it be by payment or volunteer. Then most candidates have offices in almost all major cities across the U.S. and have them staffed. So we are talking about thousand of people who are reporting to someone, who are also reporting to someone. It is one big pyramid.
How are Campaigns Paid?
They are suppose to be paid by the tax payers. Every year when a U.S. citizens pays their taxes they have the option of whether or not to donate $1 to the Presidential Election Fund. This fund was created to try and remove corporate funding of elections and make it a more fair and balanced election. But, this is only in the general election, not in the primaries. However, it is not mandatory that a candidate use the fund. When the legislation was first introduced it was much stronger, but it got watered down through the process and the U.S. ended up with a very weak campaign finance law. Therefore, when it came time for this general election to begin, and although both of the candidates had promised to us the fund Obama backed out at the last minute. McCain stuck to his promise which meant he could only use approxiametly $87 million. Although he had almost twice the amount of money as Obama in his campaign fund since he did not have a primary opponent. Obama had to defeat Sen. Hilary Clinton to become the Democratic nominee. This allowed Obama to use corporate money throughout the general campaign. Here is a web site that discuss that issue of public funding by the Federal Election Commission: http://www.fec.gov/pages/brochures/pubfund.shtml
Where their debates on TV?
Yes, they were, and there were 3 of them. Here is where you can watch them: http://www.youdecide2008.com/2007/06/13/full-2008-debate-schedule-from-dnc-and-gop-vice-mccain-obama-palin-biden-video-democrat-republican/
Although I am not positive, I think the campaign fund pays for the debates. How the debates are set up is a negotiation process between the two campaigns and the Federal Election Commission. For more question go to www.fec.gov
Also check out these to site:
Democratic Web Site: www.democrats.org
Republican Web Site. www.gop.com
Good Luck! I hope this helps.