If she decides to purchase it in CA then she would just go through the AA RTW desk and have it set up for purchase in CA. Tal Aviation would not come into the picture for that purchase scenario. Her other scenario is to set it up for purchase TLV with Tal Aviation and do it via mail/Fax/phone/inet. Check last two pages Current RTW and Circle Pacific Fares thread, on her RTW purchase and previous discussion on hold times. It actually might be good to have those posts moved to this thread since that thread went a bit off topic.

No you shouldn't be concerned about currency conversion as it is at the prevailing exchange rate (with no additional fees) on the day Dublin prices the ticket to the currency of purchase. Prices are good for 7 days. So if your reservation has been on hold for more that 7 days you will want to call AA RTW Desk before heading to Montreal and have them reprice the ticket. They should tell you all about this when you set up the ticket.

Now whether fees are charged by your CC company is another story. If you do any international travel/purchases at all then it would be prudent to get CCs and ATM cards that do not charge FX fees. Since you are from the US some choices include Schwab Visa and Schwab One ATM, Chase Marriott Rewards Premier Visa, a variety of Capital One cards, most but not all Amex, and others I am sure.