correct. the installer automatically downloads and applies the patch. if you're manually installing the 64 bit version AFTER running the installer, you're already good to go, otherwise, yes, you will need to download and apply it manually.
the universal patch is 90% identical to Zombie's patch for the original, found on strategycore. in addition to all the fixes made there, are some small, openxcom-specific fixes that are too boring to go into detail over. basically it fixes a large number of small issues in the vanilla map data.
all this said, i recommend grabbing the nightly build over the 64-bit version 1.0. there is no performance gain for using 64-bit vs 32-bit, but there are considerable improvements in the nightly that are well worth it.