Newport was a Navy basic training (boot camp) station. The Company 357 Barracks C was his basic training assignment. His company would have had over 100+ sailors to a company. This was the Navy's way of keeping track of all its new recruits. He would not use this company designation again. After completion of Navy basic training the sailors would be sent to the 4 corners of the earth depending on the needs of the Navy at that time. Some sailors volunteered for the NAG as they were promised immediate combat action. Others were assigned to the NAG simply due to the need for more NAG. In most scenarios Seaman Donovan would have been sent to additional schooling after basic training. Examples- gunnery, signals, radio school, machine, etc... which were located all over the USA.
This info should be listed on his full military record.