Hi,
Regarding the number of links - domain.com and www.domain.com are two separate URLs and hence treated separately. So its a possibility that some domains will link to domain.com and some domains will link to www.domain.com and accordingly the numbers reported will vary.
Regarding acquisition of links - Based on the evolution of links over the past 5 years and Google's stand on acquisition of links, I would strongly suggest that you don't focus on building links artificially. Instead, I would suggest that you focus on the following -
Generation of content that results in a lot of coverage - Surveys, useful information to users/consumers , interactive content are some of the elements of the website that can help generate a lot of natural buzz. IMO, citations and natural references across the web are the future (if not the present already) and keyword based linking should be a complete NO NO.
Focus on consumers - The moment we focus on consumers and come up with innovative techniques for more customer acquisition, more the word of mouth awareness and more the possibility of mentions across the web (social media channels, online press etc)
As far as competitors are concerned, even if say they are using non white hat techniques, its only a matter of time before search engines penalize them.
Regards,
Sajeet