As for the first point - yes you can absolutely trade your labor for food to participants within the challenge. To expand this idea, I feel a challenge currency should be established, along with an open marketplace for goods and services among participants. Before the month's end I will post more on the marketplace.
And to the second point - For those of you in interweb land unfamiliar with Todd's query on Thursday, he asked 'If I pay a farmer to teach me how to milk a cow, can I keep the milk and make butter from it? You can pay for any lessons or guidance without spending your resource money. Hunting guides, chartered boats, cooking classes, foraging tours, all these things are free in terms of challenge money. This challenge is a learning experience and finding outside sources of knowledge are well within its parameters.
What is at issue with Todd's query is the ownership of the livestock. As it is not Todd's cow the milk is the farmer's milk. As a settler in this land, Todd is going to a farmer and paying him to milk the cow. It is a resource he would not have available if the farmer were not caring for the cow. HOWEVER - and here is the big deviation from the first challenge - if Todd can convince the farmer to accept goods he (or his family) have cultivated in exchange for, and to an equivalent value of the raw milk, he can use it for the challenge. The goods traded must be challenge legal, and the goods received must have been cultivated or tended 100% by the outside vendor. SO - in contrast to the last challenge if someone brings a pile of tomatoes in to your work and offers them to anyone who can use them, you can give them an equivalent value of food you yourself have grown in exchange, and these new goods are challenge legal. HOwever if someone dumps a bunch of free bananas on the counter at work because they were on sale, these are not challenge legal.
Once the milk is yours you can of course make butter from it.
Suggestions on our currency name?