From what i noticed in the downtown location, If you walk in and don't need it urgently (that is you dont have a flight ticket that is in a few days then you will be asked to drop off your application in a box. They will process it and mail it back to you in 10 to 14 business days.
If you are not travelling soon, it would be easier for you to request an appointment on their site and they will call you to set up the time and date for you to go as a walk in. This way they will review your originalndocuments and return to you at the same time so you dont have to worry about them mailing anything to you. And if you want you can pay more to pick up the passport sooner