Second question: On the back of the PSU (as pictured in the link), there is an on/off switch. However, on the back of my case, there is no space for such a switch. Will the PSU still fit? (I've already double checked that the PSU itself will fit).
Thanks in advance!
The Corsair CX430 is sufficient for your needs. The power switch will be in the opening for the PSU should fit.
You should be able to tell by looking at the back of your computer if the power switch will fit your case.