No preference, or weight, is given because of the tld. Sites and pages are judged based upon content and backlinks
No problem at all. As long as you concentrate on quality, unique content and appropriate backlinks you will do fine.
no, they don't. the trick is that sites with .coms are outnumbering all other sites with the other extensions thus it is much easyer to find more .coms, thus more traffic. another aspect is that .coms are the first sites that appeared and combined with their number, it is easier to find higher ranked .coms than sites with other extensions regards