Are there any central update option, ala synaptic, or are updates and patches installed by hand ?
Not as such. The new MorphOS release is announced and there will be a new ISO image to download. In order to upgrade the system must be booted from the ISO. This can be done by either burning the ISO on a CD-R/RW and booting from it, or by placing the ISO on HDD and booting with special boot option to mount the ISO from the HDD.
When you install a new release over old one the installer presets options to upgrade (default) or to perform a new install. Old settings and installed applications are preserved on upgrade (this is possible because MorphOS has a separate directory for the OS components, allowing safe upgrading of the components).
In some rare occasions we might provide quick fixes between releases (for instance the LhA year 2011 issue fix earlier this year). These are accompanied with instructions on how to install them manually.
So in all, not as fancy as various linux distributions such as Debian based ones, but at least the upgrade process is quite painless.
Some notes: The OS is functional when booted from the CD. This way it is possible to use the CD as a rescue disc or livecd. For example it's easy to boot from the CD in case the HDD installation somehow fails to boot due to some recently installed 3rd party component. Also, since the CD boot doesn't write to the system HDD (unless if you proceed to install the OS) it is useful for safely testing MorphOS on systems that have other OS installed on the HDD already.