Depends on your motive to blog. Those tips out there are for those who would like to focus their blog onto certain keywords so that they are more SE friendly.
If you just blog for passion and would like poeple to share what you are thinking or something personal, you blog everthing...

These are the beauty of blogging where you'll find almost anything...

Yes you can and you also can with all those advertising sites out there. I am so regretful after those stupid acts that I've done after getting a ban from Google.
See yourself about the cheque here: http://forum.lowyat.net/index.php?showtopi...&#entry11562999

Decent traffic?? What do you mean by that? How many pageviews per day? 50?
They use several different ways like the trend in clickings, your IP, ad keywords you are clicking, and the ratio of clicks/pageviews. Moreover, Blogger is under Google, if you logged in to Blogger and click, it will be a stupid mistake.

Google is smart, don't fool them...

I get only near 50 It depends but it will not be less than 30....

Well, a personal site like mine is too just post something interesting. Don't quite know what is it but you'll know some topics that people just like to read... Maybe some psychological stuffs or motivating stuffs if you are blogging your personal style.

Technology blogs, blogging tutorial blogs and money making blogs are among those having good visitors number and making good bucks if they have ads...

Well, I know many bloggers out there don't like to reply to comments but I do though. Reply them at your comment place, as well as at their blog by starting like "To your comment at my post, blah blah blah, I think that blah blah blah..."

This is called interact with readers maybe at build cliques over the blogosphere and the longer you blog, the more cliques you'll have and you'll find more readers...

I don't think blogging that often (one post per day) is the key to it but the most important thing is to keep to your frequency as people might lose your beat. If I am not particularly close to a blogger, I won't visit his/her blog daily, especially to those infomative blog. To get more coverage of a post, I would go for a frequency of a post every 2-4 days.

The frenquency might depends on what blogs you have. If you have a news blog, a few posts a day might be needed and good arranging and labelling must be there as well.