One aspect I'd love, (maybe only appropriate to be romance exclusive content), would be confirmation he's still having nightmares after everything that happened in Ferelden. Returning to Kinloch Hold could prove incredibly interesting.
Yeah, agreed. So far the writers have done an admirably realistic job portraying Cullen's PTSD in my opinion, and I'd like to see them continue to explore that.
I don't know, maybe I'm weird, but that is something I would like to explore. I've been curious about it ever since Alistair talked about it in Origins. For instance, can an addicted Templar ever get clean without losing his mind? If so, what would that involve? What if it requires blood magic? How would said Templar react to that? So many questions. 
Agreed on this too. The game has established that templars are addicted to lyrium. That puts Cullen in a tough situation, but I'd rather have the game explore it than handwave it away or gloss over it.
Whether Cullen ends up overcoming the addiction or accepting that he has to live with it for the rest of his life (whether because the physical dependence can't be overcome or because the price of a "cure" is too high) it would lead to interesting character development.
I've been wanting to say this for a while, because I've seen it in a number of places (and lord knows wanting my Warden or Inquisitor to kiss the tears away is part of my attraction if I'm being honest) and I don't want to sound like I'm attacking anyone in particular, but could we talk a little bit about the language of "curing his PTSD with my love/sex"? It kind of makes me uncomfortable. I guess I'm hoping maybe some of the people in the thread with more psych background than me can, I don't know, provide us with some informed commentary about (a) the extent to which people with PTSD eventually lose their symptoms, ( b. the role their loved ones play in this, and © the (courtesy? respect?) one is required to afford a fictional person in this regard? (Parts a and b are the scientist in me seeking information, Part c, I guess, translates to "am I totally walking around with a stick up my ass here"?)
My response would be somewhere in the middle.
Loving someone does not cure PTSD. You cannot "fix" a traumatized person by just showing them enough affection or having sex with them or starting a relationship with them, etc.
That said, having supportive people is hugely beneficial to overcoming mental health challenges, and being without support is hugely detrimental. Having understanding, loving people makes the difficult times much more bearable. If Cullen felt safe, he wouldn't have to cultivate hypervigilance as he did in Kirkwall and his circumstances would work toward growth and healing rather than against it.
I doubt Cullen will ever "get over" his PTSD, in the sense that it will never be as though it never happened. That's not realistic. However, people can and do live with PTSD and experience healing. It's not a life sentence of misery.
The Inquisitor can't "heal" Cullen. But that said, I think that having the Inquisitor's support could help Cullen heal himself.