Welcome to the Forum! That’s great to hear there are hogs in your new garden – very lucky!
It’s not so much that the hogs won’t nest in the same place as their feeding place – they will. But it’s best to keep them a bit separate in case the food attracts predators. Especially if you want a Mother with young to use your box. (Although all the hogs I’ve seen sleeping in/taking over feed boxes to hibernate in have been males – it may be that the female hogs are more sensible!)
Wooden boxes are fine for either feeding or leaving for a hog to, hopefully, nest in it. If you want a hog to move in, it’s best to put a handful of bedding in the box, but hogs usually like to do their own interior decorations, so it’s best to leave more material somewhere nearby.
There is no need to put food/water into a hog box unless you want to or are trying to keep i.e. cats from the food. Hogs are quite happy to eat outside – I suspect they may even prefer it and some hogs don’t seem to like going into boxes at all. If you want to protect the food from rain, you could use a sheet of perspex balanced on earth filled flower pots, bricks or similar. Other potential shelters are plastic tables – I have some children’s ones which tend to be lower, the top part of covered bird tables put on the ground, or those plastic stepping stools.
The perspex version can be used to deter cats as well, should they be a problem, by making the height just high enough for the hogs but a bit uncomfortably low for cats.
Good luck. I hope you manage to get a set up which suits both you and the hogs. Happy hog watching!