I also switched from the iPhone two weeks ago, I later rooted and I am really enjoying the experience. Simply, rooting gives you certain permissions that you wouldn't otherwise have. You can install new kernels for better battery, new ROM's for more features and you can customize your nexus 5 even more than you already can with stock, un-rooted android.
As for how to root, you can decide whether you want to do it manually or using a toolkit however, I suggest that you should study a little and do it manually (especially if you are on a Mac.)
Posted via Android Central App