How to pronounce @ symbol?
In Spanish, @ is called arroba.
Is there any single word name for @?
It's indeed called commercial at, but when reading it in an email address you would just say at.
So for instance:
firstname.lastname@example.org would be read name at domain dot com
Interestingly, according to Wikipedia, the Spanish name aroba (from which comes the French arrobase) gets its name from a unit of weight equivalent to 25 pounds, for which @ was an abbreviation.
EDIT: so, to answer your question (because apparently I haven't) either you use just at (which is fine pretty much in any context), or you use two words.