In terms of bringing food items into Australia, it's not that these items are necessarily forbidden but they must be declared. if they're not allowed, there's no penalty (so all you've lost is the cost of the item). I imagine that the coffee will probably be OK and that the biscuits might well be.

On the other hand, if you don't declare something that ought to have been declared, then you might get into trouble.

With the shoes, the customs people might want to clean the mud off them. (This happened to me a few years ago after a golfing holiday when I went into Australia: my golf shoes had some dirt on them. So too did a couple of tees that I had, though I wasn't too worried about losing them, but no, they were cleaned too!) Of course, if you clean the shoes, particularly the soles, before you travel, then it shouldn't be a problem at all.