There are a few things to take note of here in Calloc, so it's best to cover the town completely.
Upon first entering from the east the buildings in the far northeast and southeast corners of town are apartments.
To the south of the main roadway through town is a building with two shops. The eastern shop belongs to Merry and the western one belongs to a Common Provisioner.
West of the Provisioner is a storeroom with some archery equipment, but unfortunately the room is guarded. You could push the barrels to an empty room somewhere if you wanted, but I don't think it's really worth the bother.
North of Merry's Shop is Black. Black is a mage from Bigail who sells the basic mage spells, which you should already have.
Just west of Black is the Inn. The inn is run by Rabellino, who also happens to be the mayor. He'll talk to you about some deserters who have been hanging out nearby, and he'll also give you a quest to end some raids. He'll tell you the raids have been by some Nephil who can be found in the mountains to the northeast. If you go talk to the Nephil they'll tell you the raids were actually by some Ursagi. The Ursagi can be found in the little mountain range just southeast of Calloc.
Also in the inn is Miranda, sitting in the southwest corner. If you have a high enough reputation you can get her to join your party now, but if you don't have enough reputation you'll have to wait until you've gained access to Footracer Province.
In the far northwestern corner of town, behind some trees is a small house. You'll find the Empire Deserters here, who drop some fairly nice items when killed, including an Intelligence Bracelete dropped by the mage. You don't get anything for killing the deserters, but the items and coins they drop make it worthwhile to do.