thick vmdk- thin lun

I want to learn something. I will give an example . We have 3par thin lun 30 tb total. we use esxi 5.5 vcenter and we have thick vmdk (paravirtual) on that vcenter . email 10 tb but used 5 tb - database 10 tb but used 5 tb - file server 10 tb but used 5 tb vmdk in OS

1- What is the use of real data on 3 par.

2- I can install a 10 tb virtual server ( used 5 tb vmdk ) on 3 par

3-  If ı delete the 10 tb file server . how many gb free space will be on 3par.

4- email 10 tb but used 5 tb  in OS - database 10 tb but used 5 tb in OS- file server 10 tb but used 5 tb vmdk in OS. what is storage usage rate % and i must but disk urgently ?

thanks for helping.