Could someone tell me how I can add a few custom profile fields to the mini stats block? Would I have to create a custom plugin to fetch the information for display? If so, what code should I enter?
You may have to use $prepared[fieldx] instead of $userinfo.
I actually tried it and in this particular template (and maybe others), you need to use $userinfo[fieldx]. However, it could be in other profile templates, you need to use $prepared[fieldx] as you suggested.