How would I go about making a tempo? Also, how would I make a sequencer to accurately react to the tempo meter?

I am new to this and really want to make a sequencer out of cubes to be able to react similar to how a drum machine works. I want to be able to see and change the tempo in the GUI and it affect the cubes being launched. I need the script to be able to do those two things. Also, would I be able to get a color change script when the cube is triggered? I need the script to be able to see and access the tempo meter, for the synchronization between the tempo meter and the cube sequencer, and the color change script to know when the cubes are triggered. Thanks!