Hi Heiko,
Not to burst your bubble here, but while the information you have is TECHNICALLY correct on the work sponsorship visa (THINK it's a H-2, could be wrong), you won't find many companies that are willing to do all the paperwork.
The reason behind this is the company has to prove to the Department of Homeland Security / Immigration Nationalisation Services that they cannot find an americian citizen / perment resident alien with the same qualifications within a reasonable timeframe.
And in the worst case scenario, if the DPH in the state you are going to won't recognise your out of country cert, and you would have to do the EMT course to get employment, then the company would find it very hard to justify bringing on a foreign EMT with sponsorship.
On the good news front though, in MA anyway you can transfer your driving licence to a MA one (Only country in the EU they take for whatever reason! I had to re-do my entire licence!)
But good luck, and I wish you well!