You don't need to be a expert coder, im sure not. that being said the pratical hacking course assumes just basic computer usage and is a good beginner guide.
If I had to pick between being a good sysadmin, or a good programmer. The sysadmin is a better background. Knowing how to build systems and how they work together is more important. especially how windows servers works, 90% of corporate systems are windows.
I disagree far from it, knowing how attackers attack is essential for understanding how to harden, and knowing how to defend is important on how to attack and bypass security systems.
Fundamentally computer security ( or anything really) the most important part is getting started any bit of studying is better than none.