Priya Right to some extent but it depends on what Site you are learning links from.If the site is spammy or you see low quality posts.No addition of values.Thanks/good blah blah do not go there.Yup these days use forum and other discussion communities more for referral traffic than for ranking purposes.
True, but you don't go to forums for SEO. That's just secondary. Go to forums to help out and build a rep for you and your site. Users/Forum members are more likely to look at your profile and click the link on your signature if they see that you are always helping out and providing value to the discussion. Have a good day!
Such a Do-follow forums can be found http://adidarwinian.com/forums/ or you can try searching - Do-follow forums list on google.
Instant forum links are not good! As quality forums won't allow signature from first day or first post.. you have to contribute first.