If someone else has a U.S. patent, but no international patent, can I patent in Europe?

Probably not. It does not sound like you were the first to file or that you conceived the invention.

How do I list the patents written by a patent attorney?

You can search for patents using the patent attorney’s name. Here is how.

Can anyone help market my idea?

Absolutetly. Work out from the circle of people that you trust the most.