Hey Thomas! I am a recent Mechanical graduate from California, and I'd be happy to answer some of your questions.
1) One of the key things to remember about the working world is that there are no constants, regardless of the field you get into. Some employers want to work you to the bone and pay you a 30-40K salary to do it, while others may give you a comfortable environment and start you off with 70K and full benefits. You should expect an average salary around 50K to start, but if your experiences mesh well with specific employers, they may offer more.
2) The job market right now is a little better than a few years ago, but supply is still greater than demand. Some of my local businesses have been hiring, but the majority of job requests want 3 or more years of experience. Entry level jobs in my region are much harder to find, so I may need to relocate if my prospects do not work out. If the economy is still nasty when you have your degree, be prepared to find jobs by city and keep family/friends in mind should you have to move somewhere.
3) Your first goal should be to strengthen your math and physics, if you have not already done so. Lower-division courses like statics and material science will rely on principles like moment of inertia, center of mass, and entropy, but upper division courses will demand that you apply them quickly as a fraction of a larger problem. Your college's engineering program should give you a guide for what to take, and if you need any remedial math, get it done ASAP. Study MATLAB, LabVIEW, and at least one CAD program like AutoCAD or SolidWorks. Get some programming experience as well if you can afford the time. Also, try looking for a community college that will offer your lower-division courses as well if you are concerned about the expense.
Regardless of what you decide, I wish you good luck with your endeavors!