Hello Mike,

All the questions you raise were raised when it came to set that FIB. But the main question was: how would Russia and China react and would that mean a new approach for Syria... (new is beautiful cause it is what we need but also scary...;-))

Basically, the FIB already has been engaged against one armed group: the M23.
They were in support to the FARDC and brought professional planing, operations and modern warfare to the Kivu. The results were not long to come: the FARDC and FIB just kicked M23 over 20 km away from Goma.
The question of legal ground has not really been an issue as ToE and RoE already existed. What was new with that FIB is the ToE. What has been lacking in DRC since ages is a will from peacekeepers to actually do the job. The FIB component came with the straight intention to use lethal force to impose the UNSC decisions to armed non state actors.

The Force commander gave a pretty raw but effective definition of civilian when he arrived and set the green zone in and around Goma: all those who carry weapons (AK, RPG...) are not civilians. Civilians do not carry weapons.
Est de la RDC : Tout civil portant une arme sera assimil un combattant, selon la Monusco
http://www.digitalcongo.net/article/93352
(All civilian carrying a weapon will be assimilated to a combatant. In French unfortunately)
He basically said: if you are not a police or military staff then you are not allowed to carry weapons in the area I control. Which is the basic of the Congolese law and makes the distingo between combatants and civilians quite easy.

That said, the FIB is a political tool in the first place. Its purpose is to reverse the military dynamic to allow a political dialog to take place. So far, they have been good at fighting but political dialog is stuck in the sand and goes nowhere. So military solution prevail for the moment.
Talks suspended after M23, DRC disagree
http://www.sudantribune.com/spip.php?article48515
Now the questions are: will M23 external supporters take the risk to get at war with the UN? And what will happen if UN are defeated?