Does .mobi hold any weight on search rankings? can .mobi compete with .com for search rankings or is it useless to compete? Does it need to be optimized for mobile rankings? Please advise
seo does not depent on domain extension. you can use the same seo ways with .mobi, .com, net, org, info ..... domains shortly use the normal ways for mobi domains
is there a heirarchy when a mobile device calls a search, will .mobi be first result if all else is same (although impossible same SEO) as .com?
No there currently isn't any heirarchy given to .mobi site when doing a search on a mobile device. I wouldn't mind seeing that though, it would open a new door to mobile phone search marketing.