How can I have 2 rows and 3 columns of desktops in Lubuntu? (Instead of having 1 row which is the default setting.) I haven't found a setting, yet.
With LXDE the fine adjustment of desktop appearance is reduced as compared to other non-light weight desktops. Therefore by using Desktop Pager for workplace management you will only be able to set the number of desktops but not their appearance in rows and columns.
Still, if you desperately need this there is a way to disyplay 2 rows of desktop icons in the panel by increasing the panel height from the Panel Settings (right click on the panel to open) to a value of lager than 40 pixels:
To toggle between workspaces when moving the mouse to the screen borders you may be interested in brightside that is called with the command
sets the application's options.