There are several websites that advertise for non-national pilots. climbto350.com and jsfirm.com are two of them. As for certificates, it really depends on the country and the time period of the contract. Usually the company looking for pilots, they usually use a headhunter firm to do the advertising and selection, will take care of the validations. It has been my experience that since they will have to deal with the powers that be directly anyway, they generally start the process. You will be asked to provide copies of your certificates, medical, training records, last proficiency check (pc), passport and the last several pages of your logbook, certified.
My experience has been you will have a contract which will spell out the responsibilities of both parties. IMPORTANT! Get a copy to read over well before signing it. Get all problem areas sorted out and changed IN THE CONTRACT If you don't understand something, get it explained to your understanding, before signing. Trust me, they will hold you to the contract you signed. If and when you go on contract, leave a full copy of the contract at home and take a copy with you. It will prove helpful when they try to jigger with the contract on you. And there are places that try. Also get a good handle on your accommodations if they provide that for you. Get it explained in full and if possible pictures and address. I have stayed at one place that made a South Alabama trailer park look GOOOOOOOOOD!
As for JAA being more advanced, I personally differ with that. More restrictive, yes. More advanced? I don't think so. If it was so great, why doesn't Canada adopt it? The JAA tells you what you can do. The FAA and TC tell what you can't do. There is a big difference.