I performed a PCA on the results of 4 different tests. Each test can only have whole integers as a score, and is measured on a scale of 0-5.

From what I've read, you are not supposed to conduct a PCA on categorical data, which is similar in structure to my data. However, I've also read that this assumption or rule is often broken/relaxed, as interpretation might be valuable nonetheless.

Out of curiosity I decided to simply see what would happen, and I find that my PCA generates exactly four components. Moreover, each of my test score variables load perfectly on one of these 4 components.

Loadings:
PC1 PC2 PC3 PC4
Test1              1
Test2  1
Test3          1
Test4      1


Q1: I was wondering what is happening here. Could someone (in simple terms) explain what this means and how this could be the case?

Q2: I have a list of 8 more tests which are all measured on a continuous scale. I have also performed a PCA on this data. However, I was hoping to also add these 4 tests to that PCA. I wish to do this as the results of the 4 tests mentioned above are better understood than the results of the remaining 8 tests. Would it be acceptable to include all 12 tests (8 continuous + 4 from above)?