Is it possible to play as an educated and intelligent non-mage Elf ? I mean, I am wondering because its easy to RP as an educated and intelligent Surana or mage Lavellan but it seems difficult to roleplay as an educated and intelligent Tabris or Mahariel or rogue Lavellan or warrior Lavellan. Any advice on how to do it ?
I think it depends, and it's because of questions like this that I get so annoyed with Dragon Age's inconsistency with adhering to medieval values and standards.
Let's start with literacy, for instance - most know that literacy wasn't exactly common back in medieval Europe, so there's a part of me that wants to go "Most Dalish are illiterate, because even if they had an interest in learning and regular contact with humanity, the humans they had contact with probably are illiterate and uneducated themselves. Most people would be in that time."
Of course, we also have serialized novels and famous, widely-read authors in a time where the printing press shouldn't exist, so I'mma take a shot in the dark and say Thedas doesn't strictly keep to medieval standards of education and literacy. (To say nothing of the massive libraries and piles of book we find lying around. A single book would've cost a fortune pre-printing press, a whole library would've been impressive for even a king, so given that you can't walk five feet without tripping over one...)
So, given that, it's conceivable that literacy's common in Thedas, even among the lower class. Now, would it be common for the Dalish? I think that would depend - how hostile is their environment? Dalish who frequent extreme climates would have to put more effort into survival, and thus less effort into luxuries and leisures. How much contact do they have with humans or other clans? If they have a lot, then literacy would probably be a considerable perk. And given how Dalish clans seem to be smaller communities of a few dozen people, it could also come down to the Keeper who leads them. And there are a lot of indications showing that the Dalish practice oral culture and tradition, which would suggest that they don't rely a lot on literacy...
Personally? I headcanon most Dalish as being serviceably literate, but rarely very good at it. My Lavellan could probably read, but at a very basic level, and she had even less skill with writing (God, her handwriting was probably atrocious) But between Josephine and Varric and probably even Solas, she became pretty well-read and educated.