HPS vs NIOS II

I started studying the Cyclone V SOC, and I have few questions:

1- According to benchmark doc: https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ds/ds_nios2_perf.pdf

NIOS II/f = 170MHz; NIOS II/e = 210MHz.

Why NIOS II/f is slower than NIOS II/e ?

Isn't it suppose to be the opposite ?

2- In Quartus II when I write the C program in Main ( ) I do it after launching NIOS II software build tool. So, this means my software will run on the NIOS II 210MHz processor. How can I make it run on the HPS which has ARM processor with speed = 925MHz ?

3- So far all the docs I have seen for Cyclone V were hardware. Is there some kind of programmer reference docs anywhere so I could use it in my C program ?

Thanks.