1. Safety: I use a helmet. Honestly, I'm not convinced how much concussion protection they provide, but I've had my bell rung a few times so I'm not taking any unnecessary chances. Except for the really big and bright high end ones, I question the benefit of blinking safety lights during daylight. The purpose of gloves is to protect your hands when you fall but I don't worry about that.

Locks are a topic of their own and depend on where and how you use your bike. The cheesiest of locks are about 90% effective because they force the thief to have a tool with him. Going from 90% to 99% gets progressively heavier and more expensive. There is no 100% effective lock so reconcile yourself that this is a contest that you will always eventually lose. A nice bike left all day in the same place will require the heaviest and most secure protection. The easiest ways are to leave to the lock at your commuter parking place and/or to use a semi-expendable bike for commuter use.

2. Mechanical. If you can handle your own flat tires you are at least 90 to 95% good for on-the-road repairs. Probably much higher. With just average maintenance other stuff really doesn't happen unless you crash. I think that everyone, even the most mechanically inept rider, should carry a correct size and valve spare inner tube. That way, if you puncture, a helpful rider (more common than you probably are thinking) will be able to assist you. Quick release levers can also work as tire levers. The bigger and uglier the pump, the more functional. PSI ratings on pumps are meaningless. CO2 inflators are compact and convenient to use but definitely demand practice.

3. Other. Everybody needs to have a way to carry their "stuff". Pro riders have a following car. The road racer set carry their "stuff" in jersey pockets. The rest of us use a bag of some kind. The bigger the bag the more convenient. There is only a limited amount of space behind your saddle so riders of small frame bikes won't be able to fit a very big saddle bag. If you have a really big bag, you need to sort through it once in awhile. One spring I found a banana that I'd left in my bag the previous fall. It wasn't as smelly or messy as you are probably thinking.

If I had only one pump, I'd probably pick a Topeak road morph. My second pump would definitely be a sturdy floor pump. The most important pump feature is the chuck that clamps the tire valve. Multi tools can be handy, but the more functions they have the less functional they are. Bulky multi tools sometimes won't work for the easiest of tasks, like tightening a water bottle cage. You will be surprised at how much bicycle maintenance can be done with just a 5 mm allen wrench.