When I was an exchange student in the USA, I dreamt in English quite a few times. I also have had dreams who started in French and then finished in English.
But as i dont remember my dreams often, I cant say if I have already dreamt in German.
I can easily think in another language (I think thats why I was always very quick to learn a new language at school). Here, I am writing in English and thinking in English at the same times. Some people never understood how I could do that when we had to write essays in the English class, they were like "i always think in French and then translate the text after" . This way, you can always tell the text was originally written in French...
For dreams, I think they are in colors, but I cant remember very well. I forget most of my dreams, or I cant even tell if I have dreamt or not when I wake up.
I have had several nightmares with fire and thunderstorms since I was young.
One ime I had a funny dream about fire: my house was on fire, and instead of calling the firefighters, we just started to move the furnitures outside the house. I was following my parents and my brother but wasnt carrying anything. At one point I said "Dont forget the Game Boy"
then i woke up.
I can always remember nightmares better than dreams.
I have had dreams that started in a good way and finished in a total nightmare.