DDR3 controller soft controller IP on Cyclone V GT Nios example design

Hi,

I am checking the information internally for the first and second question.

For the third question, the advantages of using soft controller is maximum flexibility to choose memory interface and support wider interface.

For more information, you could refer to document as link below:

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/wp/wp-01188-hard-memory-controller-cv.pdf

Thanks