Regarding No 2 - a good place to start is by joining the Ebid My Space Group. We can build a wider interlinked network that way. Build a large friends list on your My Space profile - make genuine friends and they will get to know you, hopefully like you! and get to know about what you sell and where you sell it.
Regarding stumbleupon - I think that's linked to Squidoo as well. You can use it to bookmark your Squidoo site so that others can find you. See this thread below about Squidoo -
http://helpdesk.ebid.net/showthread.php?t=94983