Yes - like Cloudy says, maximise your relationship with Isabella by ensuring the marker is blue and all the way to the left on the counter before the end of Act II. She should then make a return.
You can obtain Arishok's respect by telling him that Isabella is the one that had the book(relic). You've also got to be honest with him at every chance you have when interacting with him. There's good run-down of the responses needed to get the achievement on the dragon age wiki page.
http://dragonage.wikia.com/wiki/Arishok
Incidentally, the book is actually the very basis for the Qunari honour code - the Tome of Koslun.
The duel with Arishok is tough - but doable, if you come prepared with many potions and attack him at the right moments, preferably after he charges. It does take awhile, but eventually he'll fall.
Anyway, hope that helps.