News of SEO Techniques

I am not sure how much W3C validation matters for SEO? i mean its very much important or somewhat important. If everything is

good on my site still my keyword position is dropping so could css and html errors be the reason of that?

I have a question about duplicate content with a twist. When does content that is deleted expire for duplicate content penalties? Essentially site 1 has a bunch of relevant content that has been deleted and site 2 wants to use site 1's content.
Would this be original content since site 1 has deleted the content?
Does content have an expiration date once deleted? The cache still shows the old content and archive.org has the original content indexed.

Anyways, I'd appreciate any thoughts on this topic.

Hy there,
I recently found wikidweb, and I fell in love with this directory. My question is - is it worth sponsoring a category, and

given the fact that the directory can be edited by really anyone, what do you think it's future will look like?

hey guys, just started to try and get some traffic through my new website and I thought asking the community for any

recommendations would be a good idea. So far I have used private networks and blog comments but is there anything

else/better? thanks

Say if I delete a post on my WP site and repost it and get the same pretty permalink as the old deleted one, will google

count my repost as Dupe ?