1. He doesn't seem to have a great deal of difficulty with the languages themselves, so much as he does the figures of speech within them. There are a handful of nuances from Orlesian as well, that don't translate back into standard Ferelden and other things. Aside from Orlesian, he would probably be the most familiar with Anderfeln - meeting Hilda at a young age gave him a special interest in the area - and then the basic. He does have a hard time with people from the Free Marches, but that's mostly because he, personally, has a hard time differentiating the dialects.
2. Well given that he was effectively raised by templars in some fashion or another for fourteen out of eighteen years, most of what he does is related to them in some way. However, he does have some interests outside of that. Mostly it's just in stories or things outside the Chantry, or legends from other places and such. He's a fairly literal-thinking lad, which I think makes him appreciate the fantasies told by others a little bit more. He'd probably be right next to ORdhan listening to Hilda all night long if someone didn't tell him to go guard or something.
3. Well, Loïc isn't a poor fighter, but he lacks both the finesse that Raelias has, and the strength that Ky has, or the experience of either, so he would lose first. Between Rae and Kyrio.. Ultimately I think actually Kyrio would win, because he just has more at his disposal. Not to mention, he is naturally gifted at swordfighting, and simply has vast reserves of stamina. Raelias would beat him in a random encounter, but only because of surprise and a stronger ability to make use of his environment.
4. Raelias prefers histories, because he likes to try and see precisely where it was that people screwed up. He likes to pinpoint what factors made people do what they did, and how little things effected a large group of people later on. It's probably the closest he can get to psychology, effectively? Which is a useful tool of his. It also helps him try and remain relatively neutral about things, which is something he tries, and doesn't always succeed at. But that's something else. XD
5. He thought someone had actually drugged him. He had no idea what it was, because it was a side-effect that hadn't yet been considered at that point in the experimenting. It took a very long time for him to actually remember dreaming - for a while afterwards he simply did that 'fall asleep and immediately wake back up' thing that a lot of actual people do - but when he did, he was out by himself already. He's still not entirely used to it, but they don't freak him out like they did at first. He still doesn't have them very consistantly though.