A lot of the sound clips I found online are in Stereo. I recorded all my stuff in mono and have heard everything should be recorded in mono. From room tone to affects (effects), what would be the damage if I used these clips anyways? and by damage I mean would there be a problem when I later rendered the final footage and what not because some things are mono and others are stereo?
Okay, late's back up a bit.
It was advised that PRODUCTION SOUND be recorded in mono. The human voice emits from one source (through the vocal chords and out of mouth) so only one (mono) mic is needed. Foley is almost always recorded in mono as well.
Most sound effects are recorded in mono but "distributed" in stereo - identical sound on both the left and the right stereo tracks. There are plenty of sound effects that are real honest-to-God stereo sounds, but many of them are all about the ambient details - recorded in a canyon or alleyway, for example, it's the reverb/echoes that are important and give the sound character.
What matters in the final render is the placement of the sounds in the sound field, be it stereo or any of the surround formats. Dialog (and Foley) is almost always placed in the center of the stereo field or the center speaker of a surround field; this is because human brain/ears "edit" and "remix" so that we hear most sounds in the "center" (both ears) unless it is relevant to "survival" (hearing a hungry carnivore off to the left). So yes, we are always aware of where the sound is actually coming from - front, back, left, right, up, down - but placement only registers when it has importance.
Mixing a film, however, has little to do with reality; sounds are selected, edited and mixed with the entire purpose of eliciting an emotional response from the audience. This is one of the toughest jobs in sound-for-picture, to make the soundtrack emotional & impactful and yet almost completely unnoticed.