Welcome to the Forum! I’m pleased to hear you have a camera. It can be fascinating to see what the hedgehogs get up to during the night – and the cats, etc., of course!
1. What we are feeding is supplementary to what the hogs can find for themselves, so it should be o.k. to keep feeding cat biscuits. There are also various hedgehog foods around, some better than others. But the best thing you can do for the hogs is to improve the habitat in your garden for them and ideally encourage others nearby to do likewise. Also, importantly, link your garden with others. This has the added advantage that the hogs are less likely to need to go across roads. The food the hogs can find for themselves is better for them than anything we can give them. But, as things stand, what we feed is often a welcome extra. There are some tips here:
Hedgehogs do tend to visit feeding areas several times during a night, but there is also the possibility that there is more than one. It is possible to identify hedgehogs naturally, by their markings and if you are interested in trying that, I can point you in the direction of some tips.
It is well worth exploring Hedgehog Street – there is loads of information about all sorts of hedgehog related matters.
2. If the feeding station had a bottom to it, or if it was placed on a paved area which you can clean, I would say leave it. Hogs are, to some extent, creatures of habit. But on the grass, I think you would have to move it, otherwise it will become quite messy – especially if you get more hogs later in the year. I find, if there is only one it doesn’t seem to poo much, but if there are multiple hogs, they often poo in feeding stations, and sometimes even in food bowls! But also spilt food can become mouldy. So feeding areas do really need cleaning frequently. But maybe, if you found an ideal location you could get some paving slabs to put underneath, so that you could clean it. The hogs don’t mind eating near to houses and I feed the ones here on my patio, so that I can get a good view of them out of the window.
Good luck with the hog or hogs!