Yes, a script is a textfile (just like a .bat file in DOS) normally with the first line pointing out which interpreter program that is to be used, prefixed with '#!', like
#!/bin/bash
or
#!/usr/bin/perl

To make the disk writeable via ftp you need to send a 'site rw' command by ftp, exactly how to do that varies with different ftp clients. Don't forget to return them to read-only (site ro) status before rebooting.

/Michael