Hiya Sylvia
There are a number of traditional dancing shows available on Rapa Nui but Kari-Kari is one of the longest established. All the performers are amateurs from the local community but their culture and history is extremely important to them and they spend years training and working their way up the ranks in the show (and also in competition during the annual Tapati festival in February) They show a film before the show starts explaining the training that they do.
The 'theatre', like everything on the Island, is very rough and ready - basically plastic garden chairs in a large shed off the main street but there is a little bar and there are several cafes close by for pre-show dining. They perform about three evenings per week - your hotel reception will tell you which nights the show is on. From memory, the tickets are about $15 and can be bought on the door but if you haven't reserved in advance, get there early-ish to get a good spot. (Not too close to the stage if you aren't keen on 'audience participation'...)
To sum up, it's a lot of fun. Not exactly the Frank Marino 'Divas' show we saw in Vegas but very high energy, traditional music and dance featuring beautiful Rapa Nui ladies with enviable washboard stomachs and muscular tattooed local guys in very small loin cloths!!
Go for it - you will have a blast :D
Happy travels
Mandy