When Tex's daughter was helping with his gear she incorrectly identified the magazines she was carrying as holding .45 caliber ammunition. The magazines she had were for a M-4 rifle which is .223 caliber.
The drone being used to attack the Nathan James is, by all appearances, an MQ-9 Reaper drone. During the final attack it is mentioned that the Harpoon missiles on board the Reaper are radar guided and need time to lock on. While this is accurate for the Harpoon's guidance the MQ-9 Reaper series drones are not capable of carrying the Harpoon missile.
The MQ-9 Reaper attacking the James is shown carrying eight missiles. The MQ-9 is rated to carry a maximum of 4 Hellfire missiles.
The MQ-9 Reaper is not flown from a suitcase sized controller. The operating station is more along the lines of a large gaming station with several large screens and a modified flight control system.
Witt is shown operating the Reaper drone for Shaw during the attack on the James. The Reaper is only operated by the United States Air Force, Customs and the CIA. Witt is a higher ranking Army officer and is unlikely to be qualified to operate an advanced drone.
There is a version of the MQ-9 Reaper drone, known as the MQ-9 Block 5, that was designed to carry a heavier load than the standard Reaper drone. With some modifications it is capable of carrying the Harpoon anti-ship missile. Though it is true that most MQ-9's are armed with the smaller Hellfire air-to-surface missiles.