You can hire bikes through all holiday providers. It is worth checking on the quality of the bikes provided and also prewarning the company if you are particularly tall or short so they can get the correct sized bike for you. You can take your own bike, however most companies have deals with good manufactures and you are likely to be riding a book machine. If you are particularly fussy about saddles, you could take you own and fit it to the hire bike. Similarly with spd or other specialist peddals.
Holidays usually involve fairly full days, broken up with many rest breaks.
Depending on where the tour is beach stops and visits to places of interest are also planned into cycling days. If your holiday is more than a week long there will be at least one rest day, where you will be free to relax, or if you still have bags of energy take part in other local activites. There are a wide range of levels of biking holidays to suit all levels of fitness. The level is determined by how far you cycle, how hilly the tracks are and also the type of terrain covered. It is also worth giving some consideration to altitude, cycling on the high plains of South America can be lung-busting even on what are seemingly gentle trails.