Indeed. In caravan all monsters take 100% of damage. Online, unless I'm mistaken, the monsters take less damage. I believe regular G rank monsters take 65% of damage. Level 140 guild quest monsters probably take even less.
Regarding kill times, trust me, Every quest is different. Even one little flinch can change a quest time dramatically xP also, If I can be completely honest here, the reason I don't hone for attack is because I find it pointless. At most it increases attack by 100, and at least, with weapons which already have huge attack, the attack may go up by less (around 90, 50, or maybe 20, I haven't checked). Yes, technically you get more attack but I do not think it is worth it. I personally feel that honing for attack doesn't increase your attack to the extent where your kill times will increase dramatically, only slightly (provided you do your absolute best of course). This is why I hone for defense. Take the Ceadeus Regalia, it naturally has 1080 damage, and honing for attack only takes it to 11xx damage (probably less than 1150, I need confirmation), whereas honing for defense always guarantees 60 more defense points and divine protection. However, in the end it is your personal choice.
-Alternis