What are the advantages and disadvantages of cumulative vs percentage grading?
I have done both percentages and points in my career, the latter being the most recent and preferred.

Percentages:  The only advantage I can see is that, especially in high school, this seems to be the dominant way of grading, so students and teachers are accustomed to it.  Disadvantages are that students can have a difficult time tracking their progress, or knowing, for example, how well they must do on a test to keep their grade above a certain percentage.  In my experience, it also takes more time as a teacher - determining how many questions to put on a test or quiz so that percentages can be more easily calculated, for example.

As relates to programming specifically, I always struggled with the fact that I wanted programming exercises to count heavily but had a hard time making that happen with percentages.  Students, parents, and administrators expect tests to be worth more than anything else, so if I gave tests the normal 40% weight, then that left programming exercises, quizzes, and classwork (study guides or worksheets) to split the remaining 60%, and I could just never get it "right", meaning feeling comfortable with the distribution.

Points:  The major advantage of points the OP has already noted - students, parents, and teachers alike can instantly look at assignments and ascertain which assignments are worth more (I'm assuming all are using electronic gradebook of some kind), and students who want to remain at a minimum certain level find that easier to do.

Going to points solved the problem for me of knowing how much to weight each type of assignment - all assignments are weighted the same, and if I feel the assignment is worth more, I give it more points.  So I can look at how many programming exercises I assign in one semester (depending on the course, 80 to 100), determine points for those (say 10 points each), and base the points for everything else on that total.  If I determine a certain test is going to be worth 112 points because it has 56 questions, then the students see it as a large chunk, so they don't blow it off, but it is also not going to sink them if they fail it.

Rework: By extension, rework is made easier with a grading by points system.  I've also found that "extra credit" makes much more sense for students in the points system, and they are more motivated to attempt it, because they can more readily see how the extra points are going to impact their grade.