1. English is fine. Or maybe you landed in the wrong company.
2. German part would be Zurich. Big banks and more equities/fixed income-oriented. There are many more jobs there than in GVA.
3. For EU citizens with specialized skills, it is no big deal. Some paperwork + 60CHF + a couple of weeks to wait
4. Paul, Dominique and other can surely provide you with better insights on the skills quantitative finance jobs (lato sensu) will require, looking ahead (you mentioned you are quite young). In the meantime, maybe you can create a portfolio as datascientists say and showcase on github, kaggle, read PWOQF, Daniel Duffy's books and implement (code) as much as you can, etc... Practice makes it perfect, anyways. EPFL is often cited as a good university. Still, Swiss universities are not the best around.