Can the levels and difficulty of mobs be adjusted to allow a solo person to kill them
 

I was thinking of just making my own server to run off of my computer that could be my playground so to speak. I have always wanted to be able to play EQ as a single player game where I can kill everything solo including boss mobs and PoP mobs.

Is there a way to adjust the stats or something on mobs to accomplish this?

Yes, you can search for one of the various NPC editing tools on the forums and edit NPCs to be as easy or hard as you like.