Since Toad has so little movie canon and the versions of him in Classic Marvel and Ultimate Marvel are so different I have borrowed from both comic canons and developed my own ideas about how movie!Toad's powers work and what he is like.

Appearance

Height: 5'9" (This is coincidentally both Ray Park's actual height and the height listed for Toad at the official Marvel Universe Wiki. :D)

Weight: Heavier than he looks, perhaps about 180 lbs.

Body Type: Muscular and compact.

Hair: Green. He has very little body hair and what little he does have is short, soft and fine textured. (This is based on the fact that the character design is very amphibian looking and they removed Ray Park's eyebrows for the role.)

Skin: Greenish dull yellow, occasionally shading to the orange side in certain lights. (I gave up trying to reproduce his skin color in Photoshop.) Also has many blemishes that look like a cross between warts and moles.

Distinguishing Marks: Faint burn scars on his jaw and neck. A round scar on the nape of his neck, a little over an inch in diameter.

Age: About 26.

Powers

Prehensile Tongue: About 15' long and at least strong enough to lift an adult human far off the ground.

Wall Clinging: This wasn't explained in the movie, but I use the idea of grippy-textured skin on his hands and feet.

Glue Spit: Dries quickly and forms a pretty strong bond, based on Jean's reaction in the movie.

Super Jumping: I interpret this to be the result of general enhanced strength and more muscle mass in his legs, as well as some modifications to his leg bones and connective tissues.

Other Aspects of His Mutation
This is where a lot of my own interpretation comes in.

Super Strength: All of his muscles are stronger than a normal human's, though only his legs have significantly more muscles than normal.

Pseudo-Amphibious Skin: He sweats more than a normal human, which means he gets dehydrated more easily. He is also sensitive to chemicals and skin irritants.

Mutated Mouth and Throat Anatomy: He can open his mouth much wider than most people, but can't dislocate his jaw like a snake. When his tongue is retracted it is kept in his neck and upper chest, so his neck is thicker than a normal human's.

Enhanced Sense of Taste (and oral fixation): He has a lot of brain space devoted to controlling his tongue and interpreting sensory information from it. He has a habit of licking or tasting things that most people would shy away from, like trees.

Iron Stomach: He is very resistant to food poisoning or ingested toxins. Not to mention being hard to gross out. (How else could he have eaten a live seagull without getting sick?)

Backstory

Toad was conceived in the laboratories of the Black Womb Project and raised in an institution for handicapped children in York, England. His mutation was present from birth and the staff at the institution kept him mostly on the grounds to prevent him (and them) getting public attention for his odd appearance. They also went to great lengths to train him from infancy to not use his tongue; a side effect of this was massive delays in his speech development.

When he was 14 he ran away from the institution and went to London. He survived by shoplifting, odd jobs, and couch surfing with a small enclave of mutants he met there. He barely talked and told no one his real name. It was here that he picked up the nickname Toadboy, which would later be modified into his codename. He was in London for almost a year when Magneto recruited him.

He spent his first couple years in the Brotherhood being aggressively trained in martial arts, piloting, mechanics, and the basics of strategy. They also got him help to correct his lingering speech delays. He worked hard to earn the team's respect and especially to impress Magneto.

At one point he found an internet forum for mutants and developed an online friendship with another mutant there, based on their mutual appreciation of aircraft and geeky movies. Magneto deduced that the other mutant was Scott Summers and encouraged Toad to spend time online with him. He eventually told Toad of his deduction, thinking that Toad might be able to get information out of Scott or instill doubts in him about Xavier's philosophies. This project was doomed by Toad's lack of guile and naturally lead to a falling out between the young men. Later Toad would focus on Cyclops in many fights, as a dysfunctional way of acknowledging their former friendship.

He formed a close relationship with Sabertooth. At first he thought the feral mutant didn't like him, but then realized that it was a 'nobody picks on my little brother but me' dynamic. They fought more as Toad gained confidence and began to stick up for himself, but eventually Toad's powerful kicks earned Sabertooth's respect. The fact that Toad is naturally a follower and not an alpha-male type meant that Sabertooth would put up with more teasing or criticism from him than he would from others with more potential to be rivals. (Why else would Sabertooth not rip Toad's face off for all his sass in the movie?)

After the events of X-Men 1, Toad was captured. Because Toad is a British citizen Stryker arranged for his capture to remain secret and for him to be sent to the Weapon X facility at Alkali Lake. Stryker was concerned that if it was public knowledge that Toad had been captured he might be deported or extradited to England, which would put him out of Stryker's reach.

Weapon X used Toad to teach martial arts to Nightcrawler as part of their plan to kill the president. They also preformed several experiments and tests on him and determined that he had been genetically engineered. Weapon X's geneticists recognized that he was likely the work of the Black Womb Project. This led to some shadowy dealings between Weapon X and Black Womb, resulting in Toad being sent to a newer laboratory facility where he could be studied by Weapon X with Black Womb advising.

After the events of X2 when Alkali Lake facility was destroyed and Weapon X came under scrutiny they arranged to give Toad back to the Black Womb Project. While they were transporting him out of the laboratory facility Toad escaped and headed for the safehouses and contacts he remembered from the Brotherhood. He only found a few of the non-combat oriented mutants who had sympathized with Magneto since most of the fighters were taken down at Alcatraz.

At this journal's creation Toad has been free for a few weeks and is trying to find the core of the Brotherhood and separate the facts from the rumors regarding the events of X3.

Questions? Concerns? Anything you want more detail on? Drop a comment; I love to talk about my character as much as the next RPer. :)