Great question Rabidstoat especially in light of recent events.

Evacuations may vary from airline to airline so this answer is based on the way I know. I imagine it's pretty standard from airline to airline but there could be some variants.

When performing our safety demo we are scanning the aircraft for ABPs or able bodied passengers. This are people we think will be of assistance in an emergency like being able to move passengers. Should something happen I already know where to look so I can call for help and it's most likely I'll be given the assistance if asked. We know which passengers require that extra assistance.

Once the aircraft has stopped and the evacuation has commenced (regardless if on land or at sea) passengers that need help getting to the door will be assisted by crew last - other passengers may already be helping them but crew cannot until main passenger flow has ceased. This is to ensure several things.

One a crew member needs to remain at their door repeating evacuation commands so passenger know what to do.
COME THIS WAY
allows passenger to follow the voice to an exit if visability is low as well as which exits are operating as some exits could be blocked.

FORM 2 LINES (some doors it may be just 1 line)
informs passengers to make two lines as they approach the door

JUMP AND SIT
informs passengers how to use the exit

Crew also need to ensure there is a steady flow at all times at their door. If someone freezes - they will be struck at the knees to keep the flow.

Once the main flow has stopped then crew can help those who can't help themselves using an available ABP to get them to the door. Sitting down with the passenger on the crew members lap with their arms under the passengers arm pits they both go down the slide.

If you have exposed skin or use your hands to balance or slow down you could possibly get BURNT. There are deceleration pads at the bottom of the slide to help slow you down so don't put your hands out. Although it's very easily done, when I did it in a trainer my natural reaction was to balance myself and used my hand - it hurt!

Again this varies from airline to airline and aircraft so this is from my experience.

In a land evacuation the First Officer goes out the first available exit and takes some paper work with him. The captain usually exits out the rear door of the aircraft. Should they not be able to exit the cockpit they have escape hatches or windows with escape decent reels to get them out. In a ditching the pilots get assigned a specific door to exit at however if they cannot get there it's any available door.

The slide is also a raft however some doors because of their design or location are just slides only. In a ditching the slide simply opens out onto the sea and is now a raft. Once the evacuation is complete the crew member lifts up a flap to release the raft from the aircraft. A further attachment needs to be cut to move away from the aircraft but this automatically snaps when a certain amount of pressure is applied (like the aircraft sinking).

The raft capacity varies anywhere from 30 up to 60. The raft has a canopy to protect you from the weather as well as a hole to collect rain water. A survival pack is attached and contains:
Immediate action sheet
Day/Night distress flares
Heliograph signaling mirror
First aid equipment/supplies
Survival manual
Knife
Whistle
1L of water
Sponges
Bailer
Sea marker dye
Torches
Leak stoppers
Raft Management Guide
There is also a hand pump to keep the raft inflated. At the very front and rear left hand doors are beacons which the crew member must take and place in the water. These transmit various signals for 48 hours. There is also a sea anchor to stop the raft from drifting.

The roof hatch has another useful purpose. When the German Soccer team arrived back in Frankfurt from World Soccer Championship Japan/Korea someone of the crew opened the hatch climbed half through it and and hold a German Flag in his hand. I know this isn't the reason they put this hatch in.

This wasn't a hypothetical, it actually happened: Pan Am 73 . Also.
There wasn't really any controversy - removing the pilots is an effective way of disabling an aircraft.

Thank you for the clarification. "POS" is also used to mean something highly derogatory. I was trying to give birdstrike the benefit of the doubt, so I didn't want to over-react.

Except now the hijackers can fly the plane themselves and hijack in midair. So short of the captain swallowing the key or throwing it out the window, in which case the plane turns itself off and everyone dies anyway, there's no easy way to disable a plane.

Yes, but prior the 9/11, hijackers 'generally' weren't suicidal. So the mantra in those days was 1) agree to their demands 2) get the plane on the ground 3) make sure it stays on the ground.

http://en.wikipedia.org/wiki/Aircraft_hijacking

Thank you for this detailed response. How do you know which passengers require extra assistance? Is it on the manifest, or in your heads from observing passengers boarding?

Having evacuated a plane, no matter how orderly, I can assure you it is rather terrifying. Jumping into that slide is a long way down, which is why so many people tend to end up with broken bones from the evacuation. When you look down into the slide your natural tendency is to want to crouch down and scoot into it but you have to jump into it, at which point you just say, what the hell, I have no choice and do it.

How To Escape Down An Airplane Slide and Still Make Your Connection
 

Time.com just published an article yesterday on the "proper" way to evacuate an airplane via the slide.

Here's an excerpt:
The complete article, which is worth a read IMO, can be found here.

Thank you. I never use POS in the derogatory sense since I wasn't brought up that way. Nonetheless, your point is well taken and I will endeavor to use COS henceforth. @:-)

It's usually an observation from boarding as they board first and in particular if they are completely immobile would of required assistance moving from aisle chair to the seat. Generally immobile passengers are placed at the nearest non exit row to a door so they can be easily evacuated.

What do you do if you have an infant or toddler with you?

Infants you would carry and hold them as you slide. Toddlers you would either pick up or hold hand and drag then either slide with them on your lap otherwise their going down on their own. It's hard enough going down by yourself - it's unfortunately gonna be very difficult taking a infant or toddler with you. In a prepared ditching infant lifejackets are available.

That has not generally been my experience, but I may be flying on the wrong airlines.