The CLI Installer has the possibility to select the default shell. Calamares has for this no implementation and can be only set in its config.
You could set it in /etc/calamares/modules/user.conf to your preferred shell. It does default to fish.
You can also just change after the installation your default shell with chsh /usr/$SHELL
What do you mean with “more light version” ? You can simply select or untick the packages you want in the online installation.