Yes. If you can run wow and have GSE installed it will work on any operating system.
8.3 and 8.4 refer to the macro itself within those macros on the first page you will see a drop down with an option for default version. These will be numbered 1-4. Select the version you want and hit save.
As far as talents you can generally play around with them quite a bit. The only time it becomes a problem is if you add a damaging spell, remove a damaging spell or not use Crusade. Though changes are likely to result in lowered dps if you drop rotational talents. Lazy macros work just fine with any passive changes and or utility where you want to use it manually though. Personally I use the auto blessing of sacrifice in the class tree so that I don’t have to think about it.
These are not rotational spells so will not be cast on CD so as not to waste them and to not decrease your dps.
Hold shift to cast rebuke.
Hold Ctrl to cast Hammer of Justice.
Hold Alt for word of Glory.