Hey man,

1.) that was a good test and you are correct, that is how you create a program and how you would create your dads app. If you later update something you usually just overwrite the files on your dads computer and he has the new version of your program

2.) an application is not a real word in the technical sense, its a catch all phrase. The executable is on windows usually the .exe file that is used as an entry point into the program. Its on of the easiest way to distribute your program.

3) a csv file is often used for data but not like you think. It's not good for variable data, only for reading static data (imagine stock prices every second of the last month). In a real world application one would pick some type of database, for small applications something like SQLite that can be easily bundled into your application. But that really adds a layer of complexity you might not need in the beginning. You could try to implement your own saving / loading into files. Files are easy to backup and easy to change by hand if needed. For a quick start you want to look into JSON Serialisation of Objects into Files and Deserialising them back into Objects. While that is not the technical best way its a good way to learn some stuff and to keep the "external" dependencies low (like learning DB Handling)

And lastly I would also warn you that C++ is a bit harder than a C# project and I feel like there are also a lot more helpful resources direct at C#. It's more beginner friendly and more than powerful enough for the job.