From what I've seen throughout the English set up tutorial, its clear that 100 fps is generally the standard throughout most of the game. However, im currently on a system that cannot get to 100 fps, although it can consistently stay at 99. Which brings me to my question,

How major of a difference is 99 fps compared to 100? (if there is any at all.) I can only assume its not much, but I figured it would be better to ask rather than to wing it and wonder why any issues are happening regarding fps.

You're probably looking at cl_showfps framerate, which always shows 1 less frame than it really is. Use net_graph 3 to show your true framerate.

understood, appreciate it greatly!