I wear a seatbelt...
Fine I'll be serious.
1) Safety items I carry ON the bike (assuming you mean attached to the bike and not on my person) is a 90 lumen tail light, front flasher which on sunny days I don't bother using, a 1100 lumen headlight which I only put on for night rides.
2) During my commute I wear a cheap Home Depot brand fluorescent green safety vest with wide reflective stripes, and use my rear tail light on flash mode. I think the neon green color stands out the best in most situations, however in heavy leafy tree areas it doesn't which is why I run the rear light on flash. Ideally my best, or a jersey if one were made like this, should be made of two colors, Fluorescent green and fluorescent yellow, those two colors lie in the wavelength of light that the human eyes are most sensitive to.
3) The most dangerous thing about cycling on city roads is people driving distracted, and this distraction is mostly caused by cell phone use. There is an easy fix to the cell phone issue. Every modern cell phone has a GPS in it, all they have to do is once the GPS detects it's moving faster than 15 mph it shuts off the phone till it exceeds 200 mph then it turns back on. At the shutdown speed of 15 mph it would allow a runner and a cyclist to be able to use the phone, though I'm against that too since I know that both runners and cyclists are also doing their sport distracted and seen some really stupid things they do that could have gotten them killed and I'm sure have died.
4) Flashing vs solid lighting. A European study on this found that motorists had a more difficult time ascertaining their distance from a flashing light source at night like they could with a solid light source, so they made a law banning the use of flashing lights. However a joint US and Canadian study showed that flashing light was safer because it attracted the attention of the motorist to the flashing object. Personally I think the truth is both! This is why at night I use 3 tail lights, the two dimmest ones are on flash and the brightest on is on steady. During the day things change, a solid light isn't effective whereas a flashing light attracts attention much faster; so in the day I only use the one brightest rear light on flash mode the others are off.
5) Habits for safe riding? man that answer would be too long to type out here so instead here is a website that pretty much covers it all:
http://bicyclesafe.com/ The only thing I can add to this is on the section about The Door Prize, when I'm riding next to park cars I start scanning through the back window of a car first to see I can see anyone in a seat, then as I get closer I switch to the side mirror to look for someone in the driver's seat. I also ride like I do driving a car, I line up behind cars slightly to the right but so I can see their eyes in their rear view and right side mirror. I also always stay about 3 feet behind a car or truck because sometimes, especially trucks they can roll back from a dead stop. I never pull alongside any large profile vehicle like trucks and RV's, these people may never see you even if you can see their heads in the mirror. Also when I said I ride like I drive a car that means I obey all traffic laws including stopping for red lights and stop signs (in the city), and I slow down for yield signs. In Indiana they want to adopt a law that allows for cyclists to go through red lights, but only AFTER you stop first and only if you do so safely. Also depending on speed of traffic of course I will take the lane most of the time if I can keep up with traffic and if there isn't enough space to my right to ride without getting sideswiped by a car.
6) Bells: I find them useless, they're not loud enough to attract the attention of a motorist in a car, nor peds or cyclists anymore because they all have ear buds on these days. Neon flags: never saw a need for one in over 40 years of riding, though I may consider one if I do a cross country tour. Mirrors: not sure how effective these can be, I had one for awhile then stopped using it; look, if a car is going to run you over it will hit you before you could tell in a mirror, or that new radar rear light thing that's more useless than a mirror, that a car was going to that, and at the speed of car you wouldn't have time to react, and even if you did have time to react where would you go? into a curve and damage your bike and fall over only to get by the car anyways? onto gravel and loose control and crash and get hit by the car anyways? down a ravine tumbling end over end only to die from the fall? Not every place you ride has a nice wide smooth grassy area you can just turn onto to escape a car from hitting you. Full body armor: do I have to explain that one?
7) I think most battery powered lights are running for an adequate time for most night time riders, what I find inadequate is how long the battery will last in terms of years. The new Li-Ion batteries will only last about 2 to maybe 5 years tops (depending on how often it's used) before they no longer hold a charge then you're forced to throw away the light and buy another, though there are a very few lights that the light can be sent back to the manufacture and the battery replaced and a couple can even be replaced by the user, but these small batteries tend to be rather expensive. The old Ni-Cad batteries would last 10 to 12 years, but they didn't have the power nor the ability to be small enough to be of any use on a bicycle light for today's weight weenies. So I wish they could extend the life expectancy of the Li-Ion or if not possible then find another type of battery chemistry that can.
That's all I can think of for your questions.