There is no advantage to uninstalling rather than disabling. When you disable an app it removes all updates, clears the app's data, and prevents it running or updating. There is an inert copy of the app still in the ROM, but that is in the /system partition, while your apps (and updates to system apps, and app data) live in the /data partition. So removing the disabled app would not create any more space in the /data partition, and the /system partition would not get smaller, and so you would not gain any space by doing this.
Moreover, removing the original copy from the /system partition means modifying the ROM. This requires rooting, which has benefits and disadvantages, but shouldn't be tackled unless you understand what you are doing and all of the implications.
So personally I'd say disable the apps you can and leave it at that, unless rooting and modifying your phone appeals to you.
As for updating apps you don't use, in most cases it will make no difference.
