Check the ignition switch. The items you mention all revolve around a number of different circuits once they leave the IS, but the IS can cause all of them.
The biggest giveaway is the ABS and brake lights coming on. That happens when the key is turned to the Run position. In your case it sounds like it's doing so randomly, causing the ABS and brake lights to go through their system checks, just like they do after starting the car. The power windows are on a completely different fuse and circuit than the blower fan but they're controlled by the IS. If it doesn't properly make contact then they'll be random as well.
The blower not working on 1 & 2 could be a separate issue once you correct the other one, if indeed it is the IS. The way the blower works is there's resistance on any setting less than high speed, causing the DC motor to spin more slowly. If the wiring to the motor via 1 & 2 has been compromised then it could keep it from working until you turn it to high. Check the connector on the speed switch for burned or damaged terminals, check the wiring for burned or severed conductors, and the resistor coils for an open circuit. The coils will be in the airflow so that they are cooled by the air moving past them. They're usually on a single small board that is attached to the side of the air plenum, and they'll have heavy gauge wires. Follow the wiring from the motor back and you'll likely find them faster than starting at the switch. When you find them check for 12V at the appropriate terminal as you select speeds 1 and then 2. If you have 12V at the coils then the coils are the most likely culprit.