The buyer will be instructed to make the "payoff" amount in a certified check to your mortgage company/bank.
Plan on having funds available to pay your attorney and Realtor, but this is typically funded by the buyer in the cost of the property and comes out of the purchase price. Typically, the seller pays transfer tax on the property and their attorney.
I am surprised that your attorney has not gone over all of these issues with you; do not hesitate to present these questions to him/her.
Congratulations on your sale!