Ugrading for compatibility Getting NO WHERE

You should try to verify that you have an Early 2008 model (and not just one sold in early 2008). Here's how to check that:

Run the System Information application.

Click on the Hardware line to get the Hardware Overview (if it is not already visible).

The second line should start with "Model Identifier:" followed by a string like "MacPro3,1".

If the numbers at the end are indeed "3,1", then you have an "Early 2008" Mac Pro and should be able to install Yosemite (assuming nothing else is wrong).

If the numbers at the end are "1,1" or "2,1", then your Mac Pro officially cannot be upgraded to Yosemite; it is limited to Lion (Mac OS X 10.7).

You can sync a device running iOS 9 with iTunes 11.4, IF you have not applied the iOS upgrade through iTunes. If you are not using 11.4, you can upgrade to that version and still sync your phone.

I cannot personally attest to this, but the Wikipedia article on iTunes version history says that Mac OS X 10.7 "Lion" can support versions of iTunes as high as 12.2.2.25 (August 2015). but it also says that 12.3.0.44 (September 2015) is the version that introduced support for iOS 9.