1. Lenders do not pay modification companies for their services, the client/homeowner is the one who pays the cost
2. Every company is different, but there is no streamline software which is used across the board. Many companies approach the lender different ways too. The proposal given to the lender should be based on what you can afford, without being unrealistic based on your loan amount and other lviing expenses. If you work with the right company, they will tell you that not everyone will qualify for a modification, regardless of what formulas or systems one may have available.
3. Mods HAVE and CAN be done in a couple weeks, but that is strictly on a case by case basis and is mainly reserved for homeowners with a foreclosure/trustee sale date in the near future. Due to most lenders being overwhelemed at the moment, 60-90 days is a good time frame to prepare for.
4. Principle reductions are not so common on first trust deeds/mortgages. Most lenders would rather cut the interest rate drastically to bring the monthly payments down instead of writing down balances. Mass principle reductions would equate to a severe, immediate downgrade on the value of their assets, and as we all know, banks/lenders are not in the position to take anymore hits. Reducing the rate itself sets up the borrower to have an affordable payment, and assures the lender/servicer that they will again have a performing assets.
Principle reductions on second mortgages however are much more common than a first. In the event a borrower is behind and close to foreclosure, the second note holder will likely walk away with nothing, so it is in their best interest to aggressively modify the loan, which more often than first liens, equates to a balance reduction.