Question: I read in Rasabi (Temani Kisur Code of Jewish Law) that we light ten minutes before Shabboth --and that this is incumbent upon all men (ie: we MUST do it). Any input on this as a law or minhag?

Michael answers: No such thing in the RMb"M. As far as talmidei haRMb"M are concerned, it's just minhag.  Remember:  Taking Shabboth in at sheqi'ath haHamah (sunset) and not leaving it until Seth ha-kokhavim (three stars are seen in the sky) --although it is law--is already a Humrah (a stricture). 

That's why rabbinically forbidden actions are sometimes permissible during bein ha-Shema`shoth (twilight), in cases of "Sorekh gadol."  According to Rav LevTov, however, minhag ha-maqom--when it doesn't contradict halakhah--is obligatory.  He holds that taking in Shabboth at least a few minutes early is Hovah mipanei ha-minhag.  Although I disagree with the reasoning, I always try to take in Shabboth in just a few minutes before sheqi'ah.