Differences in installing Postgres 8.3.8

Hello Postgres Gurus,
I have a feeling that I might be posting the following question to the wrong site but just in case I will ask it here first.

I am comparing different postgres installation packages for Postgres 8.3.8:
On windows: the msi vs. the one-click-installer
On linux: the rpms vs. the one-click-installer

To my surprise the different installers do not install the same options and additions to the basic Postgres server, I have not compared the availability of all of the options, as I am mostly interested in the contrib modules that install the:
- xml native postgres type - libxml lib
- guid native postgres type - uuid-ossp.sql

I found that:
On windows
-no matter what installation package I use libxml gets installed by default
-the uuid-ossp.sql is a check box with the msi, but not an option with the one-click-installer ( nor does it get put down by the one-click-installer by default, without having an option)
-if I had 8.3.0 installed on a machine with the msi and I executed the 8.3.8 msi than there is a upgrade.bat I can run for an inplace upgrade, if however I try to use the 8.3.8 one-click-installer I can not do an inplace upgrade and I get an error message that says: The existing data directory (Date/time setting: floating-point numbers) is not compatible with this server Date/time setting: 64-bit integers). Which means that I need to uninstall and reinstall.

On Linux
-rpms do not install the xml type by default
-one-click installer does install the xml type by default
-uuid-ossp.sql does not get installed by either one of them and executing the sql file is looking of a $libdir parameter which I would change if I knew what it was set to in a working Postgres install

Question1:
Is it expected behavior that different installers give a different outcome?

Question2 ( much more important than Q1):
Is it possible to get an rpm build for linux that will behave like the msi installer on windows? I am looking for a consistent way that we could put down Postgres on different platforms and know that the installation will be the same. The msi installer installs the xml type by default and makes uuid-ossp available, it would be great if the rpms could do the same or put down both options by default.

Thanks,
Sincerely,
Kasia