In open position there is some distance between the two in the couple. They still hold one hand together (leaders left hand and followers right hand). Guapea is the name of the basic step in open position. Most of the rueda figures start from this position, but a few of the figures start when the partners are side by side.
Street rueda refers to the easy figures that you may pick up on the street or in a social rueda, as opposed to learning it at a dance school. These are short and fun figures to be used in typically a social rueda, on the street, at a party, and where the dancers might not know the figures already.
Modifier commands are not separate figures, but commands to modify other figures. Some modifiers add dance elements to the end of a figure. It may be a clap (“con una”) or a turn (“con vuelta”). Others are general commands that may stop the figure, or repeat it, or similar.
When the command “… y al medio” is called, everyone gets into a position facing the center. Usually this is “enchufla y al medio”, but it could also be “vacílala y al medio” or similar. When everyone is facing the center (or facing out of the circle) the directions are usually given by a la derecha(= right) or a la izquierda (= left), rather than arriba / abajo.
Caminando means walking. This is a category of commands that keep the rueda walking / rotating continously. To speed up the rotation you may hear the caller call Camina! (= walk), Anda! (= walk), Vamos! (= let’s go) or a similar spanish word/phrase for get moving.
Most rueda figures work well in combination with other figures. To do the mambo steps after a sombrero, you may call it as one command: “sombrero con mambo”.
It is also common to wait a little with the second part, to make it a little less predictable. “vacílala con giro” may also be called starting with “vacílala”, and then a little later (but before the “dile que no”), “con giro” is called. This is written “vacílala > con giro”.