They charge 2.20 per order for returns which aren't exchanged, so if you want to try several sizes or styles, it's slightly more economical to do one big order on a credit card.
One of their customer service reps told me that there is supposed to be a code for free delivery and returns within the next couple of weeks or so, but couldn't give exact dates (and obv it can't be guaranteed a particular colour and size will still be in stock whenever the code is out).
Those fit a bit narrower than some of their styles. I haven't tried huge numbers of Hotter shoes but generally seem to be between the standard and the extra wide. In those heels I needed the extra wide. The size was the one I take in most standard high street shoes, but a half size up from the size I take for Hotter's flats, if that makes sense. If you haven't used them before, have a look at the width fitting charts on their site, as their idea of standard is wider than the high street.
I think they look neutral or retro, but would be wary of pairing them with anything that potentially looks a bit too old for the wearer, with unflattering skirt lengths (they're the sort of thing where an inch or two of skirt length really does make a difference) or other poorly fitting clothes. They have frump potential, but not inevitability.
They are really easy to walk in IMO. I have a pair of Clarks Chorus Tempo, which are very similar but with a heel 1in higher - the most comfortable heels of that height I've ever tried - and the Michelles are comfortable for significantly longer.