Yes, the final level there (3stars) is 50 points. But all you need is the trait itself to be an 'expert' in that thing, and for example, win the contest.And the more asterisks, the better. I think three is the top (for now) that a skill can have. Below is my current stats with Lin, on day 289.
For right now, I believe the three asterisks maxes out a skill. There's three colors before you get to the yellow I believe; green, blue, and purple. I don't remember though the order of them when it comes to improving a "skill."
Somebody else may be able to enlighten us but even with the 26 runs I've done of this game from beginning to end, the colors were not something I paid much attention to on this screen
The colors go from 0 - I think 10, where it goes yellow and the stars are the thing.
Another example is that the girl needs the nympho trait to unlock the lust system.