Congrats on paying down quite a lot of student loans since '08 and saving a good chunk in your 401k at the same time, nicely done! Assuming you get an average bonus this year...which you probably will...this has been a pretty decent year AND you got promoted...you could maybe pay off all your student loans by end 2014 latest. It's your highest cost debt, so I would probably try to get rid of that asap, but I am very debt averse. I also don't know how student loans work and if you can pre-pay them, but if you can, then I would take all my bonus and put it towards that if it was me. Of course you should build an emergency fund as well, so I would make it an equal priority together with student loan pay down.
Your car loan is at a pretty low interest rate, and you can always sell it if worst came to worst, so I would put that as a lower priority.
Regarding buying a home, you are very young, I don't know if you are married, but think about it carefully and think about how likely you are to stay in your area for a long time. So I would put that as a lower priority as well and I would first pay of all my other debt before getting a mortgage and save up a big down payment.
Regarding your investment question, I am not too familiar with the US retirement plans, so I can't comment on those specifically, but yes, you could open a Vanguard account and invest in low cost index funds that way which is money that you can access any time (for retirmenet or an eventual down payment for a house).