I've fitted a few of these before, so I'll just back up what others and ZG002 have said. Top floor will be no problem for access, but the middle floors will need the floor taken up to get the wires through the joists. If they have insulation over the top they will need some kind of heat shield and ceramic plant pots are ideal. They stop the light and unit overheating, which pretty much stops the bulb blowing all the time.
Just be warned that having loads of halogen spots might look nice, but it'll cost you an arm and a leg in electricity for the amount of light they put out.