yes, .com domain is good.
yeah of-course, content is the most valuable part for getting good traffic, but you should distribute the content properly otherwise no value.
form my opinion, blogger is best..
do i know your company URL?
well, forum posting is not best, there a lot of things in SEO like article post, blog post more or less they has good value.
you can do it through blekko.com with easy and perfect way.
of-course do-follow, because no-follow links are not counted as a backlink..
Because those backlinks has not so much power, I mean to say those links are not so quality links that's why.
as per my opinion, try to use blekko.com
On-page optimization is very impotent for SEO, and you need to do it perfectly :)
Here are some of the link building guidelines that we should follow Should take link only from quality domains Should take link only from...
try to do 3way link exchange (do-follow).
Separate names with a comma.