As the title says,

Do we become rank 2 after changing career, or

do we become rank 2 after a given amount of xp ?

Can we go thru the same career again instead of switching over a new one?

Is this considered rank 2 if so ?

Thanks !

You are rank 2 when you get your 10th Experience point (check out page 35 of the rules). You should still be in your first career when this happens, unless you changed early.

According to the rules, if you go back to an old career you can't continue to spend career advancements, so no you really can't redo a career. A number of people on the boards don't like this, and houserule that you can.