Concerning your 3rd point:
a) use measuring tool from menu Info -> Distance Point to Point
or the Ruler/Dimension icon from left tool bar to show Info tool bar
and activate Distance (Point, Point) tool
then click start and end point of the line and find the dimension in the command history box
use snap to endpoints to be exact
b) use plugin List Entities
from menu Info select List Entities
Selection tool bar becomes active
select one or multiple entities
click on Continue action arrows from Selection tool bar (Enter may not work yet)
a new box is opened where all selected entities are listed including length of lines
Armin
investing less than half an hour into Search function can save hours or days of waiting for a solution