My thought here is that this is a causation vs correlation issue.  I don't believe that registering a domain for more than a year will have any effect on SEO.

However, if you look at well established websites, they are more likely to have their domain names registered for a longer period of time.  A well established website is more likely to be well managed and to have accumulated worthy backlinks.  As such, the well established site is going to rank better in the SERPS.  But this increase in ranking is not because the domain name is registered for more than a year.

See what I'm saying?

I do the same thing with our real estate site.  If a listing has expired, I keep the page active, but I put a note at the top saying, "This listing has sold!  Contact us and we can find you similar listings in the city."

My expired listings bring in a lot of search traffic.

Thanks.  I did look into Active Rain...should check it out again.  To be honest, we are cheap  I believe it was $30 a month or something like that.  It might be worthwhile if we are getting good links from it but I felt that I could build better links for less money.

I personally don't worry about bad code unless it slows down my page or can possibly make things confusing for search engines or readers.

If the title and meta are appearing twice this could be confusing for search engines, so I would change this.  But, if you've got things like an unclosed

here and there I personally don't think that's going to be much of a factor.

The only benefit I can see is to make a Facebook page (Google+, etc.) look more popular than it is.  If I see a business whose Facebook page has only 45 likes then I'm not as likely to like them.  But if they've got several thousand then I subconsciously think, "Hmmm...if this many people like them then they must put good stuff on their facebook page."

Just for fun I bought a thing on fiverr where someone promised to give me more likes by posting my page on their facebook fan page.  They claimed to belong to a popular band with tens of thousands of fans.  Well, the next day I got 16 extra likes all from people's whose names I couldn't pronounce.  When I checked out those fans they were obviously fake accounts that were created just to boost like numbers.

Does it help SEO?  No.  I do believe that likes on a post can influence your seo.  But Google is not dumb.  If they see that I wrote a post that is getting hundreds of likes from around the world then they likely will promote my post a little more.  But, I think they can tell if I'm getting hundreds of likes from paid sources.  If I could look at the Facebook likes I got and automatically tell that they were spam accounts, I'm sure the algo can figure that out as well.

I personally don't think that having extra likes to your Facebook page is going to do anything for your SEO.  But, if you have likes that are earned, then this indirectly helps.  For example, when I publish an article on my site, I post it to my facebook page.  If I have thousands of fans then that is a lot of people who can spread the word about my article.