Police officers do not need a warrant to temporarily detain you if they have reasonable suspicion that a crime may be or is being committed based on officer experience. Reed knew Sparky was a hype so he made contact with her as she was nodding off. When Sparky was arrested for being under the influence, the search of her clothing and personal property was permissible due to apprehension.
During the shootout at the drug dealers house, bullets would have easily passed through the walls and boxes both parties were hiding behind.
When Malloy and Woods answer the robbery call, Christmas tree decorations are clearly visible on the street lights. This episode aired in May.