[Paraview] selecting suitable file format to begin

[M.R.Hadian]

Hi
I am a new user of paraview , trying to migrate from tecplot (on 
windows) to paraview (on linux). I read the  VTK file format 
(www.vtk.org/pdf/file-formats.pdf) but I needs your guide about 
following questions:

1. My CFD code uses multi block (patched) grid with structured 
(curvilinear) grid in each block and uses collocated grid to store 
data.  Which data file format is more suitable for my data? Is it 
possible to use vtk legacy format or I should use XML for multiblock?

2. Does paraview support the Data Explorer file format which is used by 
OpenDx?

3. My wrote my code in FORTRAN. Is it possible to generate the paraview 
data file in FORTRAN or I should shift to C++ and use VTK class?

4. As I see in the mailing list, many users use python. How much python 
is necessary for a paraview user? Should I go to learn it too or It is 
just an option for advance users?

Please note that I am in the first step of changing from one visualizing 
package to another one and it is very important for me to select the 
suitable one since my students which will work on my codes should follow 
that system.

Best Regards,
M.R.Hadian