Changing the installer (the ISO) is a LOT of work (look at my and other answers here in how messy this can get: How to customize the Ubuntu Live CD? ) It is also one-time only so you will need to do this with every new release.
For adding software during installation have a look at "kickstart". It is not 100% supported by Ubuntu but you can add a seed file. Example file.
Here are some tips: How do I create a completely unattended install of Ubuntu? You can create a config file for adding software. Last time I used this it did NOT have a method on how to remove packages.
A working kickstart file can be re-used when a new release arrives. But it is also a pain to setup correctly (to test you must install with the kickstart file and failure means you wasted a lot of time).
But there is an easier method: you can add gParted to your installation after installation. Just do:
sudo apt-get install gparted
I have a post-installation script with lots of package names in it that I run after installation. It is the best method to configuring your system to what you want. I myself always install mysql, smplayer, vlc and shutter. All I do is execute a text file with lots of 'apt-get's in the file.
This is something you can repeat after every install and it requires the least amount of maintenance. Pseudo example:
sudo apt-get install vlc
sudo apt-get install gparted
sudo apt-get remove totem
Save it, make it executable, run it after the installation and all you need to do is provide the password 1 time and it will install/remove all you added to the text file.
I have played alot with creating my own ISO installer, played with kickstart but none of them come as close as just a plain text file with some apt-gets in it.
try ubuntu
install ubuntu
options on the startup.