For the first slide, you could use True/False variables for each Marker. The variables start out as False and are changed to true when the mouse is hovered over a marker. A second variable toggles every time one of the Marker variables has changed. Once all 6 are True, then the Next button is enabled. You could also add a Visited state to each Marker and enable the Next button, once all six are in Visited state. However, that would require the user to CLICK each Marker, rather than hover.
For the second slide, you can use the numeric variable that is attached to the slider. Once that variable hits a specific value, the Next button is enabled.
See attached a quick example.
