The physics
Only two forces act on the lander. Its weight m g pulls down. The engine thrust T pushes up. Newton's second law:
T − m g = m a
T = m g gives a = 0. The lander keeps its velocity, so it hovers if it was at rest. A bigger T slows a fall. A smaller T lets it speed up.
A steady thrust gives a steady acceleration. So the usual equations work:
v² = u² + 2as s = ut + ½at²
In deep space there is no weight and no air. Once the engine stops, the craft keeps moving at a steady speed. That is Newton's first law.