I'm a mortgage broker, so I can hopefully answer any questions you may have.
First of all, let me say that there are a ton of programs out there, and depending on your credit, you may actually be able to loan over 100% of your home - however, I would not recommend it. One of the easiest traps to fall into is thinking that what you're pulling out is "free" money - often times people will take out a bit - or sometimes a lot - of extra to go on vacation, buy new furniture, or other things that I wouldn't really recommend. I'd suggest you stick with taking out just enough to cover your credit card bills and any closing costs associated with the loan.
As far as things to look out for - for a second mortgage, your biggest concern is going to be fees - whether they are charged up front, worked into the loan, or a prepayment penalty. Also, watch the interest rate you are being offered. If the fees seem unreasonable or the interest rate seems incredibly high and you think that your credit wouldn't warrent such a high rate, go somewhere else, or at the very least shop around.
For a second mortgage, I don't think I would recommend going to a broker, but it really depends on your situation. You may want to just check with one to see if it would be more beneficial for you to refinance your first mortgage and just add the balance to that - but be wary, it would likely only be beneficial if you are getting the same or lower interest rate, otherwise I'd just go with the second mortgage.
Either way, shop around and get the best deal you can - and work the numbers. One company may offer less in closing costs, but the rate may be much higher than another company, see which would save you more money over the long term. Unless you are able to pay it off extremely quickly, it will likely be more beneficial for you to go with the lower rate.
Finally, once you do get all your paperwork set up, I'd be more than happy to take a look at it and let you know what I think. Obviously, you would be more than welcome to black out any personal information (name, address, social security number, ect) and either fax or scan/email it to me. I can run the numbers, let you know what I'd suggest, and make sure that there isn't some fine print that you should be aware of.
However, you get what you pay for, so although I have years of experience in the field and feel confident I will be able to at least point you in the correct direction, I can't be held liable for any advice that I may offer
On a side note, I do most of my lending in Wisconsin, so there very well may be some regional differences that I am not aware of. If there is, your local bank/broker should be able to let you know the laws out there...
Good luck, and if you have any questions, let me know!