Well it was always like that even before 2005. Conditions were always the same and gun control made things worse.
1 is correct; gangs have considerable power here, depending on state. Foreign weaponry is found here on occasion; many semi automatics illegally imported from US civilian markets and other military stuff from everywhere. Mortars, rocket launchers and anti material rifles are sometimes found with gang members.
2 is not that simple; while there are occasional bribes and favors from police to gangs, some cops are taking over some slums and creating their own extortion crime syndicates. These have been dubbed militias and along with gangs they control a lot of poor areas.
3 yeah. Big country, big guns and big borders aren’t easy to always have police coverage in. Illegal guns are always everywhere.
5 I don’t know. That was a while ago and even with socialist oriented governments (like the one which was in control from 2003-2015) it didn’t change much. Gangs are driven by individualist gains, not political or religious motivations (united they would probably be way worse).
Still the situation in 2005 was similar to what it is now (number 4). Gun control was supposed to help with that and it didn’t; it only got rid of legal weapons which people used to protect themselves. Once criminals knew people were unarmed, nothing could stop them.