I am sorry to hear about your daughter, my father also has pancreatic cancer and has been taking Tarceva I can tell you about his experience with the drug.
My dad was diagnosed with a cancerous turmor between the pancreatic and bile duct in July, 2007 and was immediately put on Tarceva 3 times a week 2 pills a day - total of 6 pills weekly. It is very expensive, since he is on Medicare and has a drug plan - they paid part of the cost but only for awhile currently he has paid roughly $1000 monthly for his perscription. That is the bad part - the good part is that in July they only gave him 6 months to live which would have brought him to the end of last year. He is still alive and still eats - they say when they stop eating that is not a good sign. I do think that his time is ending though since he sleeps alot and his appetite is starting to go and he has started filling up with fluid. But the Tarceva gave him an additional almost 5 months without many side effects and he hasn't complained of any pain - I don't know if that is the Tarceva or just him but I am greatful for this.
He does look at things and calls them by a different word - for example he will look at an egg and call it chicken (this doesn't happen often but if you decide to try the Tarceva be prepared) - I am told the medication causes this, he has had some diareha but nothing that hasn't been toleratable and can be managed with Immodium AD - the doctors can give him something stronger but it hasn't been necessary. He has some itching with can be caused by the disease and the cancer.
When my father was diagnosed the doctors said he could have had the surgery but his heart would not allow it, he could have gone through chemo - which is the second drug you mentioned - but he would have been too sick or his other choice was the Tarceva. We chose the Tarceva and I am glad we did - he originally had jaundice that is how the cancer was discovered - they put a plastic stint into his bile duct - the jaundice came back approximately 2 months later when they had to put in a metal stint at that time they said the tumor had not grown - I believe this was because of the Tarceva. The drug will not cure you but it will give more time.
If you do decide to go the Tarceva route - check their website they will help with the cost of the drug if you need it I started to go that route and the people I dealt with were very nice but in the end my dad decided to handle the additional cost on his own.
Good luck, I hope I was helpful.