Richell 94135 Freestanding Pet Gate with Autumn Matte Finish, Small

How tall ?

Is it infinitely adjustable, or does it adjust in increments? Is it easy to move, if I don't want to step over it?

Are holes predrilled to attach the sides? One from Best Choices needed holes drilled. Wonder if this is the same gate or if Rochell is different?

Is there an extension to add approximately 4 feet to the gate?