Item 1, Users should NEVER be required to enter an ID. They should instead select a name or description from a list--in a value list, selection portal or other layout design and then the system enters the ID for them
Item 2, You should not "encode" such data into your key in the first place. Define your student level enrollment key as either a number field with an auto-entered serial number or text field with an auto-entered Get ( UUID ) instead. The only two requirements you should meet here is that the value has to be unique in each record in this table and are values that will never, ever be changed.
To explore options for value lists and other methods for selecting items by name/description but having the correct ID entered by the system I suggest downloading both files of the "Adventures in FileMaking" series. They are free to download.
Adventures in FileMaking #1 - Conditional Value Lists (includes details on how to set up a basic field based value list)
Adventures in FileMaking #2 - Enhanced Value Selection (what to do when a simple value list won't cut it.)
A field based value list with ID as field 1 and a name/description field as field 2 is the simplest of many options. #1 has a detailed example of this and #2 then demo's options that use a more sophisticated design in order to provide the user with a more user friendly interface.
Thank you. That clarifies my misunderstanding of how Filemaker works.Thank you for the instructional files too.