EFRA weight is 1350 - very low!! Although so far i haven't seen anyone with any car get near it. I was at about 1380 i think with my EC. Most were up over 1400 at the first UK national. We do need to try and get as low as possible though.
PW - that is nearly exactly as we have run our cars over here (EC and MI3). Only thing we've done differently is have the PT in front of the cells - just to put a little more weight on that side of the car. You Just have to hope that you don't want to take motor out!! even harder with that size RX in there!!!
As for ratio's - well depends on the size of your track - but as i a guide we've been looking at 3.5 on about 8 and 4.5 about 7, and i know some who hav run lower than both of those!