- I do not think the forum can answer that question for you. Certainly you could do either of those things but whether you would get fewer marks or penalties for using a ready made module over a bare chip, only the college will know.
- You would not connect the 12V power to the ULN, only to the LED strip. The ground wire from the 12V power must be connected to the ground of all the other components. There is no need to connect the COM pin of the ULN to anything in this project.
- 12V LED strips usually contain groups of 3 or maybe 4 LEDs in series, each group having a current limiting resistor. If your strip contains 30 LEDs, there will probably be 10 groups, each group having 3 LEDs and a resistor.