I noticed the unofficial patch is up to b24 while the GOG release is at b23. Are there any significant changes to make updating worthwhile?

Im not sure how to install the mods/patches and still run the game using the GOG .exe...

As the unofficial patch site states, b24 adds no fixes, it just makes the patch easier to install so there's absolutely no reason to integrate the new patch on GOG version.

Quote from the site:

Updated patcher Moo2v140b24

Today I posted a new version of the patch. This build does not add any new fixes to the game however. It simply fixes some minor issues with the exe that applies the patch to the game.

The new patcher can now be run in DOS or DOSbox directly. You no longer need to run from the windows command prompt. This should allow the patch to be applied on any system with DOSbox (such as Linux and Mac OS users)."