In Yakuake’s settings.

I had to set the transparency in individual color schemes to get a transparent background.

Cinnamon or Xfce are more similar to Windows’ user interface. Between those two, Xfce is more lightweight than Cinnamon. MATE is more for people who liked GNOME 2 and want that interface over what the current GNOME is.

Cinnamon would probably be the most friendly as a new user, but I personally haven’t used it in years and I’m not familiar with its current state.