Does the subscription ever go on sale?

The base game / expansions do, but I’ve never seen a sale on subscriptions (though there are free login campaigns, which are usually like 4 days long). The good thing is: the free trial is a ton of content, especially since Stormblood was added to it. Also, I find there’s plenty of time to unsub and not miss much between patches if you do catch up, like right now myself and my friends aren’t subbed while waiting for the next event or content drop.

Are the classes/races decently balanced?

No racial differences in this game. Class wise, playing regular content (not savage/extreme/static raiding), everything is completely viable and no one will have an issue with people playing any class. The main thing to watch out for is doing your class quests to have all skills (top left of the default HUD shows current main story quest and right under it current class quest) and when a class hits 30, it unlocks a questline to change into another class and you must do that and upgrade your class, that would be the only reason anyone would be upset xD

I saw a menu option for macros, and I’d assume that’s keyboard-only?

I think macros can be used on controller as well. I can’t speak to controller too much, as I don’t use it, but I know people say it works fairly well. All I know is it’s called “cross” in the menus so things like cross hotbars are for controllers. Macro wise I’m not sure macros are used too much. I have plenty of crafting / gathering / changing classes macros, but people tend to not use them for combat actions as they have a slight delay compared to firing off actions manually.