Yes, and no.
First up, they do add a lot of weight and doubtless help with vibration. The accessories do look expensive but you are buying a heavy lump of iron with some machining. Like a lot of equipment I'm sure the headline price is set to be attractive with higher margins on the accessories. but you would be hard pressde to find a better lathe at the proce even if you add £70 for the feet.
If you have the legs, I don't, you can use legs without bench feet or with, to give a bit more height.
Unlike the DML lathe I had before, there are no through holes in the lathe bed or its surrounds, it is threaded from underneath. Also teh base is flush all the way along so if you simply put it on a bech there would be no easy way to clean out shavings or recover things you dropped.
If you go without the feet I think you will need a wooden block at each end, maybe 60 thick or a couple of thinner ones stacked and about 200x200. You would need to bolt them to the lathe bed from underneath, counter boring so the bolt heads are flush. That would raise the bed enough for clearance and give you sufficient surround to bolt or screw it down to a bench from the top. You might get away with bolting through from underneath, dependong on your bench design, but you would still need spacers to lift the cast iron bed a little.
I fitted mine to a home made bench - think large trestle - and still used wooden blocks to get a bit more height because the bench was built for a slightly taller lathe. The photo which will follow might help.
Answering your second question, I find the swivel really useful because you can turn it 45 degrees towards you for hollowing bowls or deep vases. At my age, leaning over the bed and waving a gouge about was straining my back. Much easier to see what you are doing as well. And you can slide it along. I'm a bit tight for space on my left as I work, so unless it's a long spindle job I just move the headstock along a bit. Had it about 15 months, really pleased with it and doubt I will ever need to move on.