Persian/Farsi/Dari/Tajiki

I'm 19, about to enter my second semester of college, and an air force recruiter contacted me, saying that Persian/Dari/Taijiki, Pashto and Urdu translators are currently easily employed by the government. I have a few questions about this:

1. How similar are Persian, Dari and Taijiki? If I learned Persian (the only one which I have access to classes) would I be able to understand the other two?

2. Has anyone ever made a living translating and interpreting speech and text? How is the work, what is your normal workday like, and how much do you get paid?

3. How hard is Persian to learn for an English speaker? What are some tips I should remember?

>>5
The Pimsleur course is semi useful. It goes slow, but since there's not as many resources for Farsi as for something like Spanish/French I'd recommend doing some Pimsleur lessons. Just to see if you like how they teach it.

I have a couple of Farsi things from TPB and demonoid.
>>4 here by the way