When Naruto learns the Flash ability just before he goes out to join the war, we see Naruto actually getting his foot stuck in some stone after failing at using the Flash ability. From this, we can tell that the Flash ability allows the user to move very fast, because it'd take a large amount of force for Naruto to hit the stone, crack it and get stuck in it. Where as based on concept, teleportation would not exert any sort of outward force, Naruto would shift positions in space, but his initial vectors would not change.
This moment is at 9min 39sec of episode 250 of Naruto Shippudan. Here Naruto get's stuck after hitting Kisame(Akatsuki Member) and Bee chases after Kisame as he tries to get away.
As we all know, the Sharingan further awakens based on the level of despair a user of the Sharingan goes through. Check the wiki for more info: http://naruto.wikia.com/wiki/Sharingan
The Sharingan's power, because of its ties to the Curse of Hatred, is both a blessing and a curse. The moment that an Uchiha comes to know a powerful emotion towards someone, such as love and friendship, a stressful or emotional condition brought out from losing that precious person causes the brain to release a special form of chakra that affects the optic nerves while transforming the eyes into Sharingan. After its initial activation, the Sharingan may be used freely, although it is possible for an Uchiha to lose memory of such an event and not reactivate it until through willpower years later. When the Sharingan is first activated by a user, it has a different number of tomoe (巴) around the central pupil, varying between users.
The wielder of the Sharingan, through continued use and training, changes its form further, which involves the eye maturing fully until it has three tomoe. As the Sharingan develops, the user gains heightened abilities through the heightened ocular sense. For example, they can at least copy hand movements with one tomoe, predict a person's movement and copy techniques with two and completely use the Sharingan's abilities when it is fully matured. From what characters have noted, this dōjutsu apparently "glows" in the dark. True to its name, the Sharingan and its derived forms have shown the ability to spin. It is shown that when a person awakens their Mangekyō Sharingan without a fully matured Sharingan, their Sharingan will automatically mature while developing into a Mangekyō Sharingan.