Chances are if the tiles are cracked in some areas then they did not know what they were doing. If that is the case the tiles maybe easier to get up than you think.
The best tools are flat shovel or floor scraper, and something heavy enough to break and loosen the tiles, but not to damage the floor itself.
Till you know what is underneath I wwould not plan too much. But once all up and cleaned tile is good in the kitchen or depending how much your budget wood flooring is nice too.