1. Federal and state employers generally did not do on-campus interviews at Wayne when I was there. Notable exceptions were the MI Court of Appeals, and Wayne Oakland and Macomb Co prosecutors. People who got jobs at state and federal agencies typically did so by applying on-line, or taking internships that the agencies advertised thru want ads. Plum jobs (like US Attorney positions) generally go to graduates of name brand law schools, but there are lots of jobs still available to T3 and T4 grads who can demonstrate good skills, including people with good but not great grades with good recommendations. I know a number of people who have gotten administrative law jobs in various agencies (writing draft opinions for ALJs, say). The money isn't eye-popping, but the hours and benefits are good.
2. People mean different things by "biglaw." Some use the term pretty narrowly (the Vault 100, say). I'm using the term pretty loosely to include firms of 100ish or more lawyers in big cities, even outside of NY/LA/Chi/DC. To my way of thinking as someone from a T3/T4, those are big firms--the biggest that students from a school like mine have any hope of getting into. Firms like Dykema, Miller Canfield, Honigman, Clark Hill, etc will send people to do on-campus interviews at good regional schools (WSU and MSU, eg.) These firms pay well--starting salary is $110-$120K, but they don't pay like Wall Street or DC firms, where starting salaries were $160K+ a few years ago. Your friends at Jones Day would have done better at Cravath.
3. Wayne students are not in the hunt for jobs at the major NY firms, and I think that is largely true of any T3 and T4. University of Detroit, a T4, had a very innovative program started by a Dean who was a Harvard Law grad. He divided the 3d year class into law firms, persuaded partners at very prestigious NY law firms to come to the school as 'senior partners,' and had the students handle mock cases from beginning to end like real lawyers. You can read about it here: http://online.wsj.com/article/SB117988156447211549-search.html
. As a result, he was able to place some students from his T4 school at top-of-the-line firms in NYC. This program is really the old 'exception that proves the rule.' Other than this program, even the best students from T3s and T4s can forget about prime Wall Street jobs.
Glad to hear that you want to start your own firm. I recommend that you begin talking to other solos as early as you can--before or during your first year even. Find out what courses you should be taking, and what skills you have to acquire. Most young solos do not know enough about motion practice, (too many Civ Pro courses are taught out of the Federal rules, but few young solos will practice in Fed court), don't know how to secure appointed work (criminal, family law or probate), how much money they need to start a practice, what technology they need, what kind of library/on-line research materials they will need, and what courses they should take to prepare them for the kinds of cases that solos typically get. They don't appreciate the importance of good retainer agreements (or where to get one), what software they'll need to keep track of their expenses--the list goes on and on. Also--most solos start in 'space-sharing' arrangements, but few young lawyers know about these arrangements, how to secure them, of what terms to expect/demand.
The best advice I could give you is to find some solo attorneys and ask for as much advice as they will give you. Most will give you plenty. If you don't know who to contact, call the state bar. There will be a special section of the bar dedicated to solos/small practices. That section of the bar will have a chair, vice chair and other officers who are prominent and successful. Call one who lives near you. Tell him/her: "I'm a dumb law student who has always dreamed of having my own practice. Please let me buy you lunch someplace cheap, and let me ask all of my dumb questions, and please tell me all the things you wish someone had told you when you were at this stage." Lawyers are busy, so you may endure a few cancellations, but a lot of lawyers will be willing to help you. But don't wait til second semester 3d year. DO it now, while you can still put the advice to good use.