Bidets are a hygienic way of cleaning yourself after your toilet experience. The ceramic bowls normally come with a single hole for a bidet mixer although other tap hole variations are available. Back to wall models sit on the floor and can push up to the wall whereas the alternative would be wall hung where a frame is required to take the weight of the suspended pan. This frame would need to sit into a wall or boxing/furniture.
The bidet mixers usually have a swivel mechanism on the end of the spout for accurate direction and normally have a pop up rod waste mechanism on the back to actuate the waste release.
A space saving solution would be a shower toilet such as the Geberit Aquaclean which are state of the art toilets that incorporate a nozzle that washes you with warm water and can have a additional functions such as warm air dryer and heated seats to name just a few.
Other alternatives include douche plumbing fixtures that can be installed on the wall next to the toilet and are a spray nozel on the end of a hose with a small control.