ad 4. Mine was about 35 hours. I took my time to explore & experience the game without rushing.

ad 5. Not at all. There are hardly any typical fetch quests and even if they seem to be at first, they turn out to be well connected to the main plot or the area that you're in. There is some running around, but not to the extent that you experienced it that swamp in TW1, plus the areas in TW2 are more "condensed" so you don't have to backtrack too much. And even if you do - you can admire the beautifully designed surroundings on your way back!

The import affects some background story (i. e. if you saved Adda, she is mentioned as Radovid's wife; if you killed Siegfried, knights of the Flaming Rose hate you, etc.) and you receive some equipment on the start (i.e Raven's Armour, a pair of swords).

1. Geralt of the books is neutral to the extent he could be, and compassionate to the extent he could be. But in his world, he who pays the piper calls the tune; if the king is paying the bills, the king gets the service he wants. The fictional character with the strongest parallels to Geralt is Raymond Chandler's Philip Marlowe. Chandler's quote about heroes is appropriate to Geralt as well: "Down these mean streets must go a man who is not himself mean..."

2. Imports do not make a decisive difference. You get a couple items (nerfed because they would be far too powerful with their TW1 stats in the Prologue), mention is made of at least one of your choices, and you may (or may not) avoid a fight at at least one point.

3. Triss's character does not change so much as her circumstances force her to change. She is in much reduced circumstances and quite vulnerable after the events of the Prologue. Some find her more "girly"; that may be due to the voice actor and model.

1. Geralt's (at least from the short stories I've read) not exactly what I'd consider compassionate or ruthless, and he's politically a neutral. He does, as you said, not kill all monsters - intelligent ones that co-exist with humanity are off-limits, as are rare ones like dragons. Interestingly enough, although he is in many ways the consummate guild man, that's also a bit of a facade that he adopts in order to have an excuse to follow his moral compass. For instance, he makes up the "witcher's code" as he goes along.

2. The import has basically no impact, other than a couple weapons you still have.

3. Triss as written is basically the same character (politically adept, generally the smartest person in the room) in a situation she's less comfortable in. But the voice-acting (at least in English - if you're playing in another language it will be different ofc) doesn't really fit the character very well - it makes her seem like more of a standard-issue female love interest, and doesn't do the writing justice. Apparently she's closer to how she was in the books. She's also ambiguous as in Witcher 1, but some of it is pretty subtle. Not to spoil anything, but my advice is to pay attention to the dialogue options when you (briefly) play as Triss on some of your playthroughs.

4. I think I clocked somewhere 40-50 hours on hard - I did all the side-quests and died quite a bit haha. A lot of that time is exploration, though, so it goes quicker on later playthroughs.

5. The fetch quests are basically fixed - no more "collect 20 bear asses" quests. There is some backtracking, but not anywhere near TW1 levels.

One of the strongest and most undervalued aspects of The Witcher 2 is actually its quests.

A lot of care has been given to each quest, and they all feel unique and interesting in some way. They are amazing, varied and interesting.

Even the monster contracts, which would before be a boring fetch quest in the prequel, have different twists that make them cool.

Both the main quests and the side-quests are amazing and really memorable, and that's why I don't complain about the game being shorter (the quality and care of everything are through the roof).

One thing I've noticed about the game and the first book to be published in English is that the blurbs don't seem to capture him very closely. I remember reading something in the blurb for The Last Wish about how Geralt is "ruthless" and "cold-blooded". He is indeed in the books often accused of these very things, but it's usually people who have preconceived notions about Witchers. He gets picked on a lot for being a mutant, for wandering around and only doing what he does for money (though what they don't seem to realize is he doesn't get much for doing it).

I can remember one story...I believe the one with the dragon from The Sword of Destiny, where he comes out of a ruined entrance to a dungeon he was in fighting a Basilisk and people literally gasped at the sight of him. He grins at some point in this scene and his smile is described as "blossoming on his face like an open wound".

As far as his actual behavior (preconceptions of peasants aside) he is actually very principled and doesn't really seem to relish a fight unless he is good and pissed off. He isn't really bothered by insults and often only resorts to fighting if completely cornered or knows that it is absolutely necessary...or, as I said, if he's pissed off. When he does get pissed off, he really loses control and can easily kill pretty large quantities of people (even well-trained ones). I believe I even remember him telling companions to stay away from him during fighting.

One other thing I'd point out about him has to do with the whole sex thing. It is true, in the books and the short stories, he does bed a fair number of women, but it isn't as frequently as in the games. In other words, he doesn't actively try to seduce every woman he comes across. It doesn't really jump out at me as a big deal in the books really. In fact there's even a story in The Sword of Destiny where he is reluctant to sleep with a female character and Dandelion basically gets exasperated and yells at both of them both to their faces that they should just go off and do it already.