Are all US embassy jobs internal?

I'm in canada and wish to work with the US embassy in canada. More precisely as a Commercial specialist.

I'm curious are all good jobs within the Embassy published internally and not to the public?

Are the goverment jobs permanent as in you can not get fired and will only be promoted to a job to a lower level?

What about education? If I decide to do my master degree in a USA university, will the goverment help?

I really want to work within the Commercial Trade deparment. Should I take any Us embassy job and then apply internal to a job within my field?

Help...any advice is needed

I checked all over the web to find you an answer, but here's what i was able to find out.

Per this website (http://www.amcits.com/job.asp) I saw the following: "Although many job vacancies in the Embassy are filled by employees promoted from within, there are some jobs which may be filled from the outside. Americans may apply for jobs in the Embassy but may be subject to paying taxes in both countries. Canadian citizens may apply for jobs for which they are qualified."

So, they do post some jobs, but not all of them.

The site listed very little information about Benefits, like university expenses, but if you click on each Embassy link, you would get additional data.

Good luck!!