Safe bicycle???

I do not think there are any bicycles from any of the many reputable manufacturers that are more or less safe than any others. Safety depends on the rider, traffic, and road conditions. Some bicycles might be more stable or more comfortable than others. Some are better for mounting fenders and panniers than others. Some are more rugged, and others are lighter and faster. It really comes down to the type of riding you want to do and the condition of the roads.

Regarding brakes, unless you are riding in the rain, there is no advantage to disc brakes. Coaster brakes are not widely available on bikes with multiple gears, so since you ride in a hilly area, they do not make much sense. Also, coaster brakes only work on the rear wheel, and front wheel brakes are more efficient at stopping.

Wider tires are better on less than ideal road conditions (such as the wet leaves that caused one of your accidents), but they do add to rolling resistance and, therefore, limit your ability to accellerate. A good compromise would be 28mm or 32 mm tires. They are more stable than the 23 mm tires that are standard on most road bikes, but not as slow as the 35 mm or 38 mm tires that are standard on most hybrids.

If you want a reasonably fast bike that is suitable for commuting with a rack (with or without panniers), take a look at the Specialized Sequoia. It has long chainstays, which provide enough clearance for a rack and panniers, a long wheelbase, which adds to the stability, and enough clearance for 28 mm tires and fenders (although it comes with 25 mm tires). It is not as fast as the Roubaix, Allez, or Tarmac, but it is a good commuting bike - faster than a hybrid, but more rugged and comfortable than a racing-style road bike. If you would rather go with flat bars (which are fine for rides less than about 15 miles, but on longer rides, the limited hand position could be a problem), then you should consider the Trek 7.x FX series or the Specialized Sirrus.

IF speed is more important than being able to install fenders or a rack and panniers, then consider the Specialized Roubaix or Trek Pilot. These are faster than the Sequoia, and more stable, more comfortable, but somewhat slower than the Specialized Allez or Tarmac or the Trek Madone, 5000, 1200, or 1000. The Roubaix and Pilot also have enough clearance to install 28 mm tires if your road conditions warrant wider tires.