1) World War II enlisted man = O pracinha da Segunda Guerra (Mundial).
2) I first came to Los Angeles when I got home from the war in Europe with $300 in my pocket and the G.l.
Vim para Los Angeles quando voltei da guerra na Europa com US$ 300 no bolso e o certificado de pracinha.
The term G.I. has been used as an initialism of "Government Issue" or "General Issue", but it originally referred to "galvanized iron", as used by the logistics services of the United States Armed Forces. The letters "G.I." were used to denote equipment made from galvanized iron, such as metal trash cans, in U.S. Army inventories and supply records. G.I." was also used as an adjective for anything having to do with the Army or Army Air Force.
3) Old soldiers' home = O lar dos veteranos de guerra.
4) Veterans Day = Dia dos Veteranos das Guerras.
5) The largest garrison in the country is in this town. = A maior guarnição (praça / campo militar) no país está nesta cidade.
Garrison is the collective term for a body of troops stationed in a particular location, originally to guard it, but now often simply using it as a home base.
(1) Collins Dictionary.
(2) HUGHES, John; JOHNSON, Patrick Head. Baby's Day Out movie. In Brazil: Ninguém Segura Esse Bebê. Hughes Entertainment. 20th Century Fox.
(3) Pearson Education. Longman Dictionary. 2004.
(4) MARKS, Jane. Hidden Children: The Secret Survivors of the Holocaust. Kindle Edition. Ballantine Books Publisher. 2015.