'"Installing apps" where you drag them on the applications folder and you get no progress for that copy operation anywhere.'

What apps do you install that take so long that a progress bar would be useful?

"- Photos application unable to handle even a small amount of pictures copied from my phone, crashes or freezes your machine."

I have thousands of pictures in Photos, and it has never once frozen or crashed. Are you doing something unusual?

"- Thumbnail size in file selection dialogs and even directly in Finder is completely useless."

This is adjustable.