I want to do a k-means clustering on a dataset containing 22 numerical variables between 0 and 100 and 75 observations using R. I read this post How to understand the drawbacks of K-means on k-means clustering assumptions. My question are:
1- How can I check that my clusters are Spherical or not? having 22 variables, I cannot visualize them.
2- For checking if "all variables have the same variance" do I need to test them statistically?
3- For checking "the prior probability for all k clusters are the same, i.e. each cluster has roughly equal number of observations" what should I do if I do not expect my data to have clusters of almost the same size? In other words, it is natural for my data to have clusters of different sizes.