If you are using a dynamic public IP address then you will need to setup a dynamic DNS service to keep track of it. With multiple cameras you will only need to set up one dynamic DNS service with one camera since the public IP address will be the same for each.
Army Enlistment Contracts. The enlistment contract you sign is a legally binding agreement between you and the Army. Failure to live up to the enlistment contract you sign with the Army can expose you to potential criminal or civil penalties.
All enlistment contracts with the US Military are for eight years, or longer if the needs of the service require it to be extended. When you sign up, you can partition that eight years in different ways. Very common is a 4 year active/4 year inactive reserve. Some services will allow a 2 year active / 6 year reserve, but most like at least 3 years.