Hi there! Perhaps go for a 2 tone kitchen? dark grey base units, if you love that colour and a lighter grey on the wall units or maybe white? Dark grey does look stunning with white. Alternatively, paint one wall in dark grey, with dark grey accessories (kettle, toaster etc) which will make it look dramatic and keep the units white or light grey? Then if you are worried that the dark grey will date, you only have to change the paint colour and your accessories. :-) Hope this helps.

I think either is totally acceptable. You'll have to be careful with whites, they'll make the floor look dirty as it's cream. You'll be better off with palest cream or pale warm grey on the rest of the walls. Generally cream and white just don't sit well together.

I don't know what type of floor you have but a form of wood will add texture against the white gloss. Perhaps something vintage or reclaimed

It really is a matter of personal choice. White gloss kitchens are by far one of our most popular ranges...and they have been for a very long time! I don't think it'll be a design that will disappear anytime soon. That said, matt finish has definitely been growing in popularity. It comes down to what you like the look of more. Gloss is probably a bit more 'showy' and will reflect the light around more. Matt is more subtle and softer.