So, to start, during the Berlin Airlift, the planes were sending over mostly dry food for the people of West Berlin, liquids such as milk were sent over in the very beginning, but eventually that was switched to condensed milk mostly for space efficiency (condensed milk takes up a lot less space and weighs less). There was also "Operation Little Vittles" which started as a little side project started by one of the pilots, Gail Halvorsen, to deliver candy to German children by dropping candy attached with small parachutes as he flew over West Berlin. This candy was usually chocolate or gum. As for the aforementioned non-candy food, they were usually dried when possible and there was a large variety, from my source, they are listed as "sacked grains, vegetables, frozen meats, fish, dairy products, and fresh fruits." It's important to remember that the Berlin Airlift was not just limited to food though, the planes also brought coal, industrial supplies, liquid fuel, and medical supplies aside from food. The foods they chose were chosen in other "to obtain the maximum calorie per food ton," so essentially to provide the greatest amount of sustenance possible while weighing the least and taking up the least amount of space in the aircraft as possible.

Also, I'm assuming when you say "what kind of system" that you mean the general flight plan for the planes to load cargo, fly, and unload the cargo, so let me know if I've misinterpreted that =) .

So for the trips the planes were making, it was a 24 hour process. Planes would have to depart at specific times and their flight times to fly from a landing strip from West Germany to West Berlin would be specifically calculated and would allow for a set gap time between each plane landing and taking off so workers could unload cargo (if landing in Berlin) or resupply a plane with cargo (if landing in an airfield in West Germany). These were approximate, but they provided a general schedule for everything and helped the efficiency of the system.

And finally, to answer the question on how they made sure all the West Berliners were getting food. The source I've found is questionable, so some verification from somebody else would be great. Anyways, it seems that after the cargo was unloaded from the planes landing in West Berlin, the cargo would then be transported to distribution centers that would be throughout the West Berlin area to ensure that people had access to these centers and could receive said cargo.

And I think that about covers it, here are some nice sources:

The Airlift! This one provides a pretty solid overview of the entire airlift, if you want a nice, quick summary, this is a good place to start.

Berlin Airlift-A USAFE Summary Provides a lot of details (it's government stuff!) that you can't find on the standard website. If you're looking for something specific, this would be a terrific source. However, it is a bit of a pain to get to a specific page ._.

Berlin Airlift This is the questionable source that I used to answer your last question about how people made sure everyone was getting food. Its explanation on food distribution seemed reasonable though. However, like I said, some verification on my answer to that particular question would be preferable.