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I see different results when searching on an iPad and when searching on an iPhone.  Two different devices for sure but one is connectiing through my home network and the other through a wireless signal. However, that does not surprise me nearly as much as getting different google results from a single computer when using  IE, FireFox and Chrome.  I also connect remotely to a computer at my office in the same town but with a different ISP and get some differences in results there. I do not believe that there is a standard google anymore. Just like the TV commercials that show very different types of guys using PCs and Macs Google knows this too and serves them different results. Heck.... when I visit websites now that are entirely unrelated to SEO I am seeing SEOmoz ads in the Adsense.   Google recognizes me and serves me Fishkin's ads on the fly.... but somehow the people at Moz have not told Google that I am a member and that they can turn the ads off.    

Spamming, but I assume you're looking for something more long term If it's not that competitive then you're not going to need that much to rank. You might be able to get away with some directory and article submissions to give you enough linking domain diversity to rank, but if you can get a few quality links in as well I would guess that could do it. Really there's nothing different you need to do for low competition keywords, you just need to do less of it

The structure of your site will help determine which links are shown once you have sitelinks, but structure alone will not help you get sitelinks in the first place. Normally sitelinks are your top level pages, so navigation and internal linking to reflect those you most value would place some emphasis on which ones Google may choose to show.