Thank you, I will take the feedback into account.
The coin increases the base value of souls by +2, which starts at 1 pt. Additionally, each soul has a multiplicity value, such as 1 pt for blue souls, 2 pts for red souls, 3 pts for purple souls, and 10 pts for yellow/golden souls (the golden soul appears with a certain level of randomness starting from level 2).
So, for example, a red soul would give you 2 pts initially (2 pts of multiplicity * 1 pt base value). If you then upgrade the coin once, the base value of all souls becomes +2, and in the case of the red soul, it would be worth 6 pts: 2 pts of multiplicity * 3 pts of base value. Basically, the more you upgrade the coin, the more points you get for each soul in play. In the future, I'll work on improving the player's experience to provide this information more clearly.
I will address the rest of the points in future versions. Thanks for playing!