Many US paratroops would have been dropped by a Douglas C-47 Skytrain (also known as a Dakota), this was a derivative of the Douglas DC-3 commercial airliner. A slightly different version was called the C-53 Skytrooper, this was also used but in smaller numbers. Early in the war commercial DC-3 aircraft were converted to C-47 specification (mostly removing the passenger seats and installation of a larger cargo door at the rear). The C-47 was also used to move important cargo/supplies.

In terms of the specifications, the Boeing site has most of the figures you ask for here: http://www.boeing.com/history/products/c-47-skytrain.page

The British did use the Dakota (this was the RAF official name for the C-47) but they also used a wooden glider called the Horsa to transport paratroops and equipment (such as jeeps). The Horsa was cheap and easy to build as it didn't require lots of engineering machinery as a normal aircraft would. They are probably best known for being used by the Oxfordshire & Buckinghamshire Light Infantry in Operation Deadstick, which was one of the first landings on D-Day.

The objective of Deadstick was to capture the bridges over the Orne river and Caen Canal to make it difficult for the Germans to get reinforcements to Sword beach, where the army was to land just a few hours later.

The Ox & Bucks did a superb job and the operation was a complete success. The bridge that crosses the Caen canal is now best known as pegasus bridge. There is a small museum near the actual landing point that has a re-creation of a Horsa glider, see : http://warmemorialtours.com/pegasus-bridge-tours/horsa-glider-replica-pegasus-bridge-museum-1944.jpg

The Horsa could carry up to 25 paratroopers and took 2 crew to operate. It could be towed at speeds of up to 150mph and could glide at as much as 100mph.