A witch's "Labyrinth" is technically a separated space which the witch hides in, as such, it doesn't so much have a range. We see this numerous times - no matter how far they travel inside a witch's Labyrinth, the Puella Magi more often than not reappear where they entered.
In the case of the first witch whom Mami faced together with Madoka and Sayaka, in which Mami saved an office woman from falling, the three entered the Labyrinth when they were on a bridge. After the witch was defeated, they reappeared on the same bridge.
Charlotte's Labyrinth appeared outside the hospital where Kyousuke Kamijou was in. Sayaka and Kyubee traveled a fair way into it to reach where Charlotte was asleep and kept a watch on her progress. Mami and Madoka also did a lot of traveling to get to Charlotte's lair. Despite all that, all of them sans Mami returned to the same spot that Sayaka and Kyubee had entered.
Homura's Labyrinth was inside her Soul Gem and contained in an isolation field which we see isn't all that big despite it being the size of an entire city (though it did have a limit which would then loop back into the city). We can confirm this when the Puella Magi broke open the roof and there were 2 Incubators looking down.
The case of Walpurgis Night, however, is different. In the timeline before the anime, which Kyubee commented that Kriemhild Gretchen would finish destroying the world soon, Madoka is seen inside a Labyrinth where Homura was fighting Walpurgis Night. However, at the end of the series/second movie, the fight took place in the city without the materialization of a Labyrinth, we can make 2 hypotheses from this:
Walpurgis Night's Labyrinth is that of the storm cell that weather agencies picked up and warned people about.
Walpurgis Night gets more powerful with each jump Homura does due to it being a possible cause for Madoka's Fate. In its final fight, its Labyrinth probably wasn't needed since next to nothing could stop it. However, its power doesn't grow nearly as fast as Madoka's, which is why after enough jumps, Madoka could kill it with one shot.
As for how much control a witch has over the elements in the Labyrinth, they don't have much apart from the formation of elements that they use for their attacks (e.g. Sayaka's wheels). The Labyrinth is more of a reflection of the Magical Girl's mental landscape before she became a witch. We also know that a Labyrinth forms before the witch is fully born, which is also the case of Charlotte whose Labyrinth had formed but was still sleeping as a Grief Seed even when Mami and Madoka entered (we see Sayaka and Kyubee keeping a watch on it).
Sources: Observations, Madoka Magica Trivia