I'm sorry to hear about your hardship, and I definitely feel that you're putting everything you have into your family right now. I think that before you spend any money, let your fingers do the walking and call some attorneys and simply ask about pro bono work and tell them your circumstances. Since your family may meet the requirements for free legal assistance, you should not overlook the possibility of getting some free help with your case. In your situation, I think an attorney and the right judge are the only things that can help you.
In my "opinion" you should at least file to use the MFA method and use your two children. I think it is purely wrong to allow children of a divorce to have a better lifestyle that other children. And that is exactly what the guidelines currently do with respect to the MFA. If the family changes, cash flow changes, and therefore child support changes, period.
With respect to additional employment, I think the way it works is this: if the family relied upon the additional income before the divorce, then it is included. If there were not additional jobs before the divorce, it will not be included. BUT, in your case, the economy is terrible, and also, you work, so your husband may not physically be able to work 2 or 3 jobs. And I don't think the court should force him to work many jobs either. Family is important, and kids are only kids for a short amount of time. Its hard to hear that judges are essentially requiring fathers to maintain many jobs away from home and their family so they can pay for a lifestyle that simply isn't the same anymore.
There is no hard and fast rule about the employment, the guidelines simply use more vague language by stating that the "court may consider...." blah blah. All that means is that if the judge doesn't like you or your attorney, you are hosed. That should not dissuade you from asking for absolutely everything in your motion. I apologize for the terrible analogy, but think of it as a price negotiation for a used vehicle. If the price is $5000, and you want to pay $4000, you don't ask for $4000, you ask for $3000, then it sounds like a wonderful deal to everyone when the agreed price is right in the middle ($4000). You should be asking for much more than you anticipate because the judge will probably meet in the middle somewhere. Sorry for the analogy, but I think we all know that's how the real family court system works.