I basically agree with Cari115, but you don't even NEED a lawyer. It's your choice, to protect yourself if you feel it necessary, but I for one didn't use a lawyer and I'm not regretting it. I and my ex were civil. The divorce wasn't easy, but we were civil.
As for the mediator; Save your money. Anything a mediator can do, you and your STBX can do yourselves. If you can't agree on things now, a mediator will most likely not help anyways.
-------------------- I didn't get married to pay CS later in life.