Closing cost can vary, in part, depending on whether you choose to have impounds(your property taxes and insurance being built into your payment). If so, your lender will hold back x number of months worth of both. The x will vary depending on the time of year. In addition, closing costs typically will include your portion of title & escrow, your appraisal, pre-paid interest(the time from your close to then end of that month..close later in the month and you'll have less), whatever costs your broker and lender charge and your recording fees. A good rule of thumb is to figure up to 6% of your pruchase price.
As for your second question, the seller pays a pre-determined percentage or dollar amount to the buyer's agent. That is typically disclosed in the agent's MLS system. While I can't directly help you in Orlando, you're welcome to email or call if you'd like. All of my information is in the link below. Good luck