You can have separate HUDs for them, but you do need to buy them separately. PC version doesn't work on Playstation or the other way around. Don't think you need separate subs for them tho.
I've been playing from start to end of Stormblood so far on the PS5 with a controller and have had no issues at all. It works very well on the controller. I did have to change the settings around quite a bit to set it up as i want it, but that was all personal things so don't know if you will need that tho.
I would recommend a keyboard as well for when you do dungeons and raids because chatting with a controller doesn't really work very well