Hi,
It will be difficult leaving her alone for this amount of time; with working a full-time job, but you can do it.
Working dogs need exercise, and be prepared to spend at least 45 minutes a day, taking her for walks. This will "tire her out", calming her down, and will be a great benefit in training; such as when to eat, poop, etc.
The previous answer gave some very good links and information.
I would like to add the following:
As a new puppy owner, I highly recommend a video by Ceaser Millan, a Professional Dog Behaviorist. He rehabilitates dogs, and trains people.
He has his own TV program, the Dog Whisperer, on the NGEO (National Geographic) channel, on Friday nights mainly, but also comes on some other days. This video is available from:
http://www.dogpsychologycenter.com/
I also ordered his new book, "Ceaser's Way", from Walmart online, around $15 US, and it's very good!
There are other good videos available on the web, but this one is really worth your attention.
Ceaser Millan's TV program addresses the "working dog" class in almost every program. Your mixed breed puppy is definitely in this class!