Can red wine stain a Polished Concrete floor?

Just like any other floor type, red wine will leave a stain if not attended to straight away.

Is it possible to have a polished concrete floor in a domestic house which will not crack and make the polishing ugly? Can concrete be reinforced to avoid cracking?

A structural slab and topping slab or screed should be reinforced but even with these measures there is no guarantee that the concrete will not crack. If your foundations move the slab will move which may cause cracking.

What happens if someone spills petrol or turps on a Grind and Seal or a Hyperfloor?

Wipe as soon as possible with a damp cloth.

Can you polish existing slabs?

Yes, we can Machine Polish or seal existing slabs.

What about aggregates in concrete mix? What is generally available and what is recommended?

Can concrete flooring be put over ceramic tiles in kitchen and bathrooms and how do you clean it?

If you have an existing concrete slab you can certainly remove the existing floor tiles and then Mechanically Polish the concrete slab.

When do you add the colour?

Colours are added by the concrete supplier and are in the mix before the concrete sets.

What type of things can we throw on the top of our slab to make it more interesting?

Coloured pebbles, different sizes and types of aggregate, glass beads, steel, brass again this is largely limited by your imagination.