cosmaar1,
I feel your pain. A couple of years ago I had a hose blow under the machine. I got to lay in the mud created by hydraulic oil and struggle to replace it. It seems like it would have been easy from the top.
Anyhow, I have never taken the mat out, so I do not know for sure (I think NH575E has tho), but from all indications, the cab has solid floors, except for the heater box hole.
Below is from the manual, and it preaty much says the cab must be removed to carry out the tasks, one of which is hydraulics.
I can tell you, in the future I may look into cutting the floor for access to the hydraulics. My hoses are over 20 years old and will surely fail at some point.
If anyone has cut the floor to gain access on a NH E series, I would love to hear about it too.