I would get with a Credit Union and discuss refinance options. 18% is killing you on that balance. Too much of your payment is interest.
Paying the $100 extra is going to get you $1200 closer to paid off. You mentioned doubling...is that out of the picture now due to cuts at work?
Also, this is a good time of year for a SPRING CLEAN garage sale or ebay sale or craigslist sale or all of the above. Sell some stuff....we all accumulate stuff we don't need, don't use, don't want, don't remember is even there, is a luxury we can do without, in the attic, closet, under the bed and gathering dust while losing value. People raise from hundreds to even thousands depending on their accumulation of "stuff" so look around and take advantage.
You also may want to consider looking at selling the car and buying a less expensive pre-owned through a Credit Union at lower rates. You'll have lower balance and less interest, lower payment too. You have to decide on that based upon your equity position in the vehicle.
Do you have savings/emergency funds? With work cuts, I would seriously consider getting into a lower priced auto, lower rate and start saving some reserves just in case the pay cuts become job cuts. 
Always have a plan b in the works when you can....all or nothing, best of case scenarios are not the best way to plan going into law school meaning you have less time and more expenses.
Some might. 100k is a threshhold which would keep you out of many lenders. I would call around. Try Alliant, PenFed and any locals you want to try. I would explain the school part and wanting to reduce interest and accelerate payoff in prep for school. Leave the job cuts part out
Right now I wouldn't deplete your cash reserves. And I would probably suggest putting a little extra into it each month. If you can double down on the payments, maybe you go 60-70% more and 30% to savings just so you have some discretionary cash. For now you need to enjoy the best things in life which are free, and save your cash or pay it to debt....so get a written budget and a tight belt
Also, if you put your cash (current and ongoing) into a savings account with the Credit Union (and direct deposit check if possible) this will add substantially to your credibility with them and increase chances of loan and better rates. Bank and save where you get service and credit and appreciation for the relationship.
