Zeal actually mostly focuses on artifice. Alchemy was simply the most relevant commission to her interests. She didn't pick the plague because it was alchemy, but because she wanted to focus on the plague. Helping with the plague was something Zeal felt she needed to do. The most relevant commissions to Zeal's skills are the boat and festival commissions. She will try the bank commission even if her skills are not the best aligned.
The contract put on the table is that fill-in template DeTess mentioned. It's just an example to give an idea to Z of what to expect to sign. It's not the final contract. Zeal will need to write a new contract to match the odd circumstances.
That's right! OOC, Z should get the money from his commission, because that is only fair. I think it'd be a jerk move and not a team move OOC to try to take Z's comission.