1) The European schools have the toughest standards. Many (or most) Asians and middle-easterners (and some Australians) train in the US, which has a large, readily available, and relatively cheap general aviation infrastructure. US general aviation is larger than all general aviation in the rest of the worrld combined. Also US airspace is freely accessible in most locations, without a lot of taxes or excess regulation.
While European JAA training standards are higher, it is very costly. Some is even done in the US, to JAA standards, to reduce costs.
Generally you want to get licenses for the nation in which you wish to work. European and middle-eastern airlines which routinely hire foriegners will usuall accept either FAA (US) or JAA licenses.
2) There are many variables here. First, you will not be able to work in many countries unless you have citizenship or a work visa. Even then, unless you are a natural citizen and well-connected, it may be hard to get a job. You always have an advantage getting an airline job in your native country.
Asian and middle-eastern airlines often hire foriegn pilots due to their own shortages (caused by lack of general aviation). However, these are usually experienced airline pilots, usually US, British, or Australian.
In the US, if you can get a permanent work permit (greencard), you will be able to compete equally with US pilots...if the job market is booming, you could probably get hired at an airline appropriatte to your experience level.
As far as pay, there are many factors. Benefit packages, retirement, work rules, and time off are all important factors.
European airlines probably pay better than many US airlines at the entry level, but top pay will be lower than the best US jobs.
The middle-eastern airlines usually have good pay and benefit packages.
Many asian airlines only hire foriegners on a contract basis, so there is no guarantee of lifetime employment...this not good since your seniority at a company determines your pay and time off.
FedEx and UPS are probably the best compensated airlines in the world. Most other cargo airlines are marginal or worse. Also, cargo airlines which do not run their own door-to-door package-delivery service like UPS/FDX usually depend on contracts, which can shut down the airline if cancelled...this has happened at least once in 2008.