I'm afraid I'm away for work until Wednesday, so I'll have to apologise for the delay and do air systems and pressurisation in more detail then. A couple of points to keep you going though:
1) In most airliners, air is taken from the engine surrounds and fed into the cabin. Because this is hot, it is usually cooled first by air conditioning packs. There are several of these and one alone can do the job. Temperature is set on the flight deck, so if you are really too hot/cold, tell the cabin crew - if they are any good (and the point is reasonable) they'll tell the flight crew who can alter the temperature. Some airlines (cheapskates) try to cook people in the cabin by keeping the heat higher than it should be - less work for the air conditioning packs uses less fuel = more brownie points.
2) Air density at 38,000 feet is considerably less than at sea level. So much less that there is insufficient oxygen to sustain consciousness in the average human being. In an airliner at 38,000 ft therefore, you need more air density than the ambient density (which is more than enough to fly the plane - just not enough to breathe). It is achieved by pumping air into the cabin at a greater rate than it is let out the back. The outflow (and thus, pressure) is controlled by valves. On most airliners, there are separate types of valve and separate control systems, so all should not be lost at once. This rule may be changing on the new A380, which has several valves from the same manufacturer. The point is, the systems are duplicated.
3) When the cabin is pressurised, you cannot open any doors or emergency exits - even if the nutter in row 9 tries, you'll be perfectly safe. The pressure holds them in place and they will only release once the plane has been de-pressurised.
4) In the extremely unlikely event of a sudden depressurisation, the flight crew will usually put on oxygen masks (passenger masks may also drop - depending on how high you are - put them on straight away - and do yours before helping anyone else, you may have only a short time of useful consciousness). The pilots then turn the aircraft off track, select a safe altitude on the auto-pilot and maximum rate of descent. Because there may be some sudden condensing of water in the cabin (misting), the steep rate of descent coupled with some vibration from the speed brakes (helping to increase the rate of descent and keeping the aircraft below the maximum handling speed) the whole maneouvre will almost certainly scare the life out of passengers - whether or not they are usually fearful flyers. What you need to know is that these incidents are very very rare and that the flight crew will be managing everything for maximum safety using the automatic systems to reduce the risk of human error. Your ears may hurt like hell and your heart may be doing overtime, but this type of incident is very unlikely to kill you. I have asked several pilots about this and I have yet to meet one (personally) who has ever experienced a cabin de-pressurisation for real. They do happen, just not very often, and a good number of those that do are not very dramatic, because they comprise of the cabin failing to pressurise properly when climbing (in which case the climb is just stopped early and, if the destination can be reached at a lower safe altitude, the flight will continue).
5) But what about the Helios accident in Greece? Well, I just don't know about that. It was almost unique as an incident and a whole thread on here has been subject to substantial contribution from people far more qualified than I. However scarey it sounds, I would try to put in the the context of many thousands of flights taking place safely throughout the world every day.
6) Even IF you were slow to put your mask on, you may become unconscious. So long as the pilots descend the plane in a timely fashion, you will simply come around again when there is sufficient air density.
7) So, a VERY RARE event, one of the few that can be genuinely alarming for all concerned, but you are unlikely to suffer anything worse than some lasting deafness (in the event of a perforated eardrum).
Any pilots whose companies have different SOPs for this, I'd be interested to hear about them.
HH