Ok. You use the built in unity 2D.
No, sorry. Right now there is no included movement script that works in the XZ plane. However following the get started tutorial you should be able to convert that to use the XY plane instead.
I am working on adding some 2D movement scripts.
[EDIT] In version 4 of the package the built in movement scripts work in 2D worlds as well. Take a look at https://arongranberg.com/astar/docs/pathfinding-2d.php