Translation of zelebrieren

Can you translate: Are you using the firefox browser? Install this tool in your browser window. The ones I suggested the other day are the most useful ones, because we would use it for generic terms which differ from Spanish.
In plural there is no difference between the formal and the colloquial address form. Do you mean that you are using 3rd person singular form for the plural imperative? If so, I will change all entries so far.
Have you ever visited the U.S. before and if so, where have you been in the U.S.? I've been travelling in California, it was very amazing. We have traveled by car. Here are my corrections.