100/120hz televisions do not play well with games. the tv is incapable of accepting a true 100/120hz signal so it post processes and adds frames in. this can lead to noticible visual lag which is why it is often recommended to get a 50/60hz screen instead
the only screens capable of true 100/120hz input are the 100/120hz tn panel pc monitors that use duallink dvi. however tn panels are generally regarded as low end.
no screen is going to increase your FPS, only your hardware can do that. keep in mind that you dont want less than your refresh rate in frames per second but having more doesnt help you either. you could be playing at 150fps but on a 50hz screen you lose 2/3 of them. alternatively with less FPS than HZ you could be seeing a few double frames. this is why some games lock at your native refresh rate and will only display 50fps with a 50hz screen.
as far as mci... http://www.google.com/#hl=en&output=search&sclient=psy-ab&q=100hz+mci&oq=100hz+mci&aq=f&aqi=g1g-b1&aql=&gs_sm=3&gs_upl=2546l4593l0l5453l9l9l0l0l0l0l281l1748l2-7l7l0&gs_l=hp.3..0j0i8.2546l4593l0l5453l9l9l0l0l0l0l281l1748l2-7l7l0.frgbld.&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=555e839155bb5ffd&biw=1038&bih=409
my guess is that its some proprietary thing by lg which you dont need.