Note that this is in no way mandatory - other chapters have servers hosted in all sorts of places. Typically the US, which is of course *the* place for cheap noncontroversial hosting :-)
Sure, but the WMF servers seems to best place to get started. Maybe once the chapter is a little more established it might be worth looking into other options, but a simple wiki on the WMF servers will do perfectly well for now.
I agree with Tom here - the WMF servers are the best place for now. Perhaps after we've been going for a while, we'll be able to buy toolservers etc., which would then be the obvious place for hosting the website. But the WMF is the best place for an incubator site for the fledgling-WMUK-that-just-got-some-wings.
Mike