It will take about 5 pounds of cut up clothes (that is, with
decorations and seams removed) to make a normal sized rug of about 22"
diameter. Obviously that will vary some by what kind of material you
use, but that gives a good general idea.
With my stitches, about 1 foot of strip comes out to about 1 inch of
sewn row.
2) An old flat handled toothbrush OR a small cheap paintbrush (1/2"
head is about ideal.) Either way, you'll chop off the head/brush
part, sharpen the point into a needle (as tapered and smooth as
possible), and drill a hole on the other end, or enlarge the extant
one, as large as possible without weakening it.