Hi Mark,
If your desktop searchers and mobile searchers have similar interests and intents, and use similar keywords to locate similar concepts, then responsive design will be an adequate solution for mobile SEO. In most cases, however, mobile searchers have different needs and use different keywords than desktop searchers, and sites constructed with the principles of responsive design without addressing mobile users and keywords will have decreased engagement and be eligible for fewer keywords than a site that has an optimized mobile home page and site architecture with additional pages for mobile-specific visitors. In that sense responsive design is a step towards optimization, but will never be as optimized as a well-optimized mobile site. See my recent column in Search Engine Land for an example of how Walgreens designed their mobile site in a way that addresses mobile searchers concerns in a way that responsive design will never be able to: http://searchengineland.com/how-to-best-optimize-your-mobile-site-for-seo-112940
That article outlines the process I recommend for optimizing mobile sites to be truly competitive in mobile search, so that should answer your first question. As for the others...
> do I need to submit a mobile sitemap to Google?
No, but it doesn't hurt. As I explained in another SEL article about mobile SEO myths:
These can help with indexing feature phone content, and for letting Google know that you want your content to appear in their index of accessible mobile content. But if you’re indexing smartphone content, you don’t need it, says Google’s John Mueller. To back him up on this, none of the ranking sites in the upcoming Resolution Media study on smartphone search results used mobile sitemaps.
Mobile sitemaps probably can’t hurt, and like Web sitemaps, they could help sites get more unique content indexed, but they’re not necessary for mobile SEO unless you’re concerned about indexing feature phone content.
**>Do I need to link from the mobile page to the corresponding page on the desktop site and vice versa? **
No, but it is a best practice from a usability standpoint as some searchers are going to prefer your full site. Especially if they can't easily find what they're looking for on your mobile site.A link from your desktop site helps with search engine discovery, so it is helpful, though not completely necessary from an SEO standpoint.
>Will Googlebot Mobile naturally find the site from the desktop link?
Maybe, but it's better to properly redirect Googlebot mobile and smartphone Googlebot to your feature phone and smartphone sites, respectively. I would also verify your site(s) in Google and Bing Webmaster Tools, as in my experience that is the fastest way to get new sites indexed.
>What about link building for mobile sites, any thoughts on this, are there specific mobile sites that will link such as directories for a start?
I wrote an article on mobile link building at Search Engine Land, giving five easy steps for beginners:
http://searchengineland.com/better-mobile-linkbuilding-in-5-easy-steps-86410
It contains a link to my blog, where I have a list of several hundred mobile directories
>Any other tips or resources? Any SEOMoz resources on this?
Rand doesn't believe in mobile SEO, as he's under the mistaken impression that search engines are platform agnostic, in spite of the the evidence to the contrary. As it is, there hasn't been much written here on the subject.
Would definitely recommend reading more of my column, as you have asked a lot of questions about things I've addressed in my column in the past. The other columnists who write regularly on mobile search at Search Engine Land also give great advice.
Here are a few more resources to check out:
My Natural Search and Mobile SEO Blog, where I've been writing about mobile SEO since 2007
Cindy Krum's Mobile Moxie site, that has tools and info on the subject
Sherwood Stranieri's Bars of Signal blog
Interview with the three of us on BlueTrain Mobile
Covario also has a good white paper by Michael Martin
>What about the same domain versus the subdomain debate about hosting the mobile site? Any thoughts?
If you want to spot a newbie to mobile SEO, ask him/her if mobile pages split link equity and prevent mobile pages from ranking. The concept makes sense in theory, but mobile content is a different paradigm, and properly redirected pages will actually appear in search results as of December 2011 regardless of link equity. And Google had been doing a pretty good job prior to that distinguishing mobile pages from desktop pages and displaying the most appropriate content: http://searchengineland.com/dont-penalize-yourself-mobile-sites-are-not-duplicate-content-40380
As I recommend in the how to article above, an m.domain.com site is preferred for mobile homepages and other mobile-specific landing pages. For all transcoded desktop content it's fine to use responsive design with the same URL.
Hope this helps!
Best,
Bryson