Correct, I started the game without a budget so I've been relying on Patreon to pay for art. Sarah's art is actually in progress now, but may not be until 0.18 depending on how schedules work out.
There's no time constraint currently. Time tracking is mostly to give some sense of duration to the adventure, though in some future content there may be time limits (ex. 7 days after you start a quest to finish it). But in general, you can just do whatever you want.