Rate and Term 
This is a refinance of your first mortgage with no cash out.  Up to 95% of the value of your home at conforming rates.  If you have a 97%, or 100% mortgage, and your home value has gone up - you should refinance in most cases.
      
Cash out
Generally you can take out up to 75% of the value of your home without a rate bump.  Over 75%, you will see a small rate increase to the rate (up to .25%).  You can take up to 100% of the value of your home, but the rate is a couple points higher, and the credit restrictions are higher.

Under normal rules, you can take out up to $100,000 out of your home and keep low rates.  $200,000 is available at a slightly higher rate.  Unlimited cash out is available, but generally it's an ARM (adjustable rate), not a fixed rate.  There are no limitations on the cash uses.
  
Debt Consolidation 
Make your debt tax deductible.  Use your biggest tax deduction - your home.  Whether with a 1st or 2nd mortgage, both work to your advantage!

2nd Mortgages 
usually for debt consolidation - see above

Conforming rates means under a $300,700 loan amount.  Jumbo rates are a little higher.

Non-conforming rates are for people with credit issues.  Depending on how bad your credit is, the rate may vary.