Damn Jeremy, sure is some sucky pics.
I'm not sure what they are, except for number 2. This is a TVS (thermal vacuum switch). This is too route vacuum to whatever is hooked up to it. The way it works is no vacuum until the engine temps are around 160 degrees. Say the TC is hooked to it. This means the the tranny won't lockup until the engine is around 160. Same thing with anything hooked to it. My truck came stock with two, a black one in the intake coolant passage and the gray one in the thermostat housing.
If number one and two are on the firewall, the one on the firewall behind the brake booster is the low vac switch for the TC clutch power.
The one on the passenger side is the tip in vacuum switch. On LE9 engine equipped vehicles with automatic transmission a "tip in" vacuum switch is used. Its function is to provide a momentary contact closure (signal) to the ESC controller during a throttle "tip in" condition which then briefly retards spark timing to minimize knock. The switch contacts are normally open under steady engine vacuum conditions including no vacuum, and all brief increasing vacuum conditions. Basically the switch closes only during rapidly decreasing vacuum conditions such as that encountered on rapid throttle operation.