There seems to be some confusion here about visas. Essentially here is what you do if you would like to work in Spain and are a US citizen. This is accurate as I have been through this process. Of course, exceptions will apply.
1) You need an official 'Oferta de trabajo.' This is drawn up by your potential employer in Spain and is certified by the Ministry of Labor in Madrid. Take this and the following to a Spanish consulate and arrive early:
1) Passport with 3 photocopies and 4 photos
2) The application form from the consulate.
3) Letter of good conduct from your city's police (in NYC this is downtown at police HQ).
4) The oferta and a copy
5) A medical certificate which is clear that you are not ill physically or mentally, not a drug user, do not have the plague, yellow fever, or cholera. Be very thorough with this.
After this expect to wait for 3 or 4 months. Then you have your visa and can go to Spain (if you are not there already, in which case you must return to the consulate).
Once you have the visa, when you arrive in Spain you must apply for a residency permit. This is done at the police and will take a long time as well - I am waiting for this at present.
Questions and answers:
1) You cannot do this from Spain nor can you have the consulate mail you things. Do it before you go, or expect to fly back and forth a lot.
2) Get a gestor, which is a lawyer type to help you with the paperwork. All in all, Spain is no worse or better bureaucracy-wise than any other country, however you will save time with a gestor.
3) If you want to look for jobs:
www.infojobs.es. A big employer with a good legal department will help immensely as they will have dealt with this before.
4) Other questions feel free to email me.