Translation of diabolisch

You can always write me and we can learn together any language you want. How long you have taken classes? Was it only at night or on weekends? Makes me wonder how someone can be so fluent in Spanish.
I met the company last autumn, because the site's traffic is getting pretty big and they invited me to a workshop. They have convinced me that I have to put their logo at the top of the page to maximize exposure and this was a big mistake.
Thank you for your email, everything was crystal clear. We should call each other, this would be the best way. Do you have the same opinion? But I think I need more help, for example: how do you conjugate swim?