You want to commit to one and put a 301 on the other.  Googlebot should be smart enough, but it isn't really.  Some things aren't best to be left to chance.

Here's the Moz 301 redirect article: http://moz.com/learn/seo/redirection

Edit: Here's another article about www.mysite.com vs mysite.com http://www.stepforth.com/resources/web-marketing-knowledgebase/non-www-redirect/#.UlbGl1Cko2s

Browser Size is a good one for extrapolating devices, that can be more helpful than a list of smartphone brands or video game systems and other tv browsers.

It's good practice to include spacing but Google can make the distinction.  That being said, I would recommend just using spacing and no pipes if you don't have space for three characters it looks much better.

The Google webmaster blog published an updated guide four days ago [link: http://googlewebmastercentral.blogspot.com/].  I'd recommend following it to the letter.

Another thing to watch out for when changing hosts is to make sure your DNS settings are ready to go on your new host before you cancel your old one.  These days this is usually fast, but I've seen sites go down for ~48 hours because they didn't take this precaution.  I'm not sure what your level of computer savvy is, so here's an explainer on DNS and why it's important [ink: http://www.howtogeek.com/122845/htg-explains-what-is-dns/].  Basically it's how your browser translates a URL into a form that it can understand and provide a page back to you.  Most hosts provide this free, and it's something you never think about until something goes wrong with it.

It's important to include a small logo, that way if the graphic is not correctly attributed to you, it is still associated with you or your company.  Include a small non-obtrusive logo on the bottom of the graphic.  Professional photographers, infographs, etc. usually include a logo, and perhaps a link.  Just be sure that including it doesn't take away from the graphic.