When new variables are added, the package specification will need to be updated. Parameter values are stored in a table that speeds access with very little cost in parsing. The cost is a larger table and complex code which must be maintained. The speed benefit is lost in most applications where parameters are accessed only once. WebAda scripts access parameters extensively and benefit from the increased speed.
Compilers usually take input from a file.
In the case of the GNAT compiler, the name of the file must match the name of the unit, with the extension, .adb or .ads. As WebAda matures, the file name may be generated automatically for you. In the meantime, become familiar with the compiler's way of dealing with file names.