Bandwidth monitor:
Look no further than MRTG:
http://www.mrtg.org
The Multi Router Traffic Grapher (MRTG) is a tool to monitor the traffic load on network-links. MRTG generates HTML pages containing graphical images which provide a LIVE visual representation of this traffic. Check
http://www.ee.ethz.ch/stats/mrtg/ for an example.
Download Manager
Look no further than
wget. If you know how to use wget then you'll appretiate that wget is the best download manager