Why MPM ITK recommended?

Hi!

We operate with Cloudlinux 7.2 and configuring EA4. We often work with Shopware, which is a onlineshop software from Germany. So I read their performance guide:

In other words, in EA I can choose between MPM Prefork and MPM Prefork + MPM ITK (module) as described in cPanel documentation:

Now I just have a few questions:

1) Why do you recommend to use MPM ITK when using Cloudlinux? Because in all benchmarks I found, it's much slower than MPM prefork. What is the technical reason? (not for being slower; for choosing MPM ITK)

2) I already enabled CageFS. As I read a big plus of MPM ITK is the separating of the vhosts directly in Apache, while CageFS creates a virtualized file system and cages scripts done by apache. But is it necessary to use both techniques? How do they work together?

3) Choosing MPM ITK, in cPanel CGI (not FastCGI) is the only available handler, right?

4) Cause I'm using CGI instead of suPHP it's fully compatible to OPCache and APC, right?

Thanks in advance!