just for the sake of clarity.
GPL does not have to be free.
anyone can charge for a program that has a GPL license. YOu just have to give the code to them when you do and keep any copyright statements there may be in the code.

also, ftp is still very important if you are going to be running websites.

there are going to me many times that you will not be able to do certain things any other way.

also, using the file manager in your cpanel ( cpanel is a brand name and not every host uses it) or whatever your hosting control panel is, can and will corrupt certain file types like php.
things like wordpress and bulletin boards etc are written in php.
things like dreamweaver, frontpage etc. will also sometimes corrupt php files if you even open them.

so, if you are going to be responsible for running and maintaining websites then you really should have the basic tools and learn how to use them.

luck,
robert