I understand that in order to craft something I convert its worth into silver, multiply the dc by your roll, and subtract that number from it's worth in silver to determine your progress. This represents progress made during a week. How does time pass during this week? If I had a party member do this would they be allowed to participate in adventuring until the next week where they'd roll again, or are they completely dedicated to crafting for this period?
Talk to the DM
Without corresponding rules for making Craft skill checks, an argument can be made that none of the above is strictly necessary, but most DMs won't go for that. Instead, a house rule might look like this:
A reasonable and appropriate place will vary based on the Craft skill employed as the difference between where one plies his Craft (blacksmithing) skill and where another his Craft (poetry) skill will be vast. Further, as craftsmen start new tasks without first completing old tasks but can return to incomplete tasks and complete them, the last part of the magic item creation rules appears burdensome.
Even a generous DM will probably prohibit making faster or greater progress on items if the character spends 2 or even 3 8-hour shifts using his Craft skill. The game prefers characters do one thing at a time, rarely rewarding overtime.
The house rules detailed above don't prohibit simultaneously crafting and adventuring, but make adventuring secondary while crafting.