You can use the keyboard to quickly switch between the layouts in the drawing, simply hold the CTRL key while pressing the Page Up/Page Down buttons, such as CTRL+PAGE DOWN to move to the right of the tabs.

Remembering selection sets is just as easy as points (above).  Use this syntax at the command prompt to remember a selection set.

Command: (setq sset (ssget))

Whenever AutoCAD requests objects to process within a command, simply provide it again with the ! prefixed symbol.

Command: MOVE
Select Objects: !sset

To remember a point (assign it to a variable), use this simple syntax at the command prompt.  This assigns the point you pick to a variable named ‘pnt’.  You can repeat this procedure to store several points with symbols like ‘pt1’, or ‘pointone’.

Command: (setq pnt (getpoint))

Anytime you want to refer to that point within the same drawing session, simply prefix it with an ! at the pick point prompt.

Base Point: !pnt

When you have multiple object snaps turned on that can be in effect for a given object (such as quadrant and center on a circle), you can press the tab key while hovering over the object to change the snap.