Hi metallicaguy1. There (pretty much) are no dumb questions
Spiking/clipping into red in the Reaper meter is something you want to avoid by lowering the input when it happens, as you are doing. So you're doing the right thing. But as far as do you need to, it depends. It might be an ever so slight clip of barely a few samples, which Reaper will register but may not be audible, depending. Or it might be a fair doozy of a clip, where an entire syllable is smashed, and the result is undeniably ugly. Or something in between. If you have a great performance and the track meter flicks the red barely and you can't actually hear anything terrible at the spike, you can usually of with it, especially if there are other things happening at the time. For that reason a clip during mix down can be more troublesome than a clip on a single track of many where other things are coming down at the same time. But, yep, if it's more than just a tiny lick of clip, and especially if you can sing it again and not feel like you've lost the take of a lifetime, back off the input, sing it again, and adjust the previous level down to match this new lower level.
When people talk about "headroom" they're talking about the space on the meter between where most of the audio is hitting and the 0db clip. If you don't leave enough headroom, when you shout a loud part it can clip, so you want to leave enough headroom, even if it looks like you're recording at a low level. It will be fine and the loud parts won't clip.