No it is not necessary to have a business permit or license to sell merchandise at any kind of convention.
No, you need a license from the holder of the trademark.
I would say you need to contact the owners of the logo's trade mark and negotiate merchandising rights.
get what everybody wants on it and ask what do they want or they can get there own
Yes. Logos are registered trademarks of the team. You would need the permission of the team to sell something you made that has the logo of a team on it. How do you go about getting permission to use team logos? And do you need permission to use team fight songs? The NFL actually has a web site set up to answer this question. Take a look at www.nfl.biz for all of the information that you'll need about licensing an NFL team logo.
Depending on the age you start to breed green frogs.
If the logo (especially if it contains a 'mascot') is copyrighted, no, you cannot sell them for profit without a 'release' to do so from the school administration. If it is un-copyrighted the name of a public school is considered to be in the 'public domain' and you may do so. In either case, it would only be common courtesy to contact the school administration and get their view on the matter.
If the painting is still protected, you would need a license.
You would first need a business license in the locality you are selling the merchandise. If you are producing the apparel yourself you'll need to form a licensing agreement with the New York Yankees and Major League Baseball. If you are reselling officially licensed apparel just the business license will do.
Some colleges handle their own licensing; some have hired companies like the Licensing Resource Group to handle it for them. If you are looking to license a logo for one particular school, I suggest that you use a search engine and search the terms +logo +license +[name of school].
Try contacting them directly for information on how to replace it. There will be a contact page on the merchandise page.
You need a driver's license to drive, and insurance on the vehicle you're driving.