No, commenting on nofollow blogs will not provide you the backlinks. However you can drive the relevant traffic by commenting on niche blogs.

If PR is good then nofollow link can boost your SERP.

dont worry about it. Just get the link

by any means necessary

I assume NoFollow backlinks is not so useful than DoFollow.

Traffic is all for the success of any Internet Marketing. You will get traffic from NoFollow blog comments. NoFollow blogs have very small number of comments. If your comment be relevant, interesting, informative then you will get direct traffic from that site.

So NoFollow blog comments have positive effect on SEO.

As you know that google only follow do follow links and give backlink for website. On other hand bing and yahoo follow all links. But no follow links are also beneficial for getting traffic. So do not worried about do follow or no follow. just make more and more backlink.

Getting nofollow links makes your site look more real and relevent in Google's eyes. go for it.

I believe it's always important to have some mix when it comes to dofollow and nofollow backlinks, and nofollow links are a good way to mix your anchor text as well, so as to make it appear natural

Commenting on no follow blogs doesn't provide you with the backlink

Ya nofollow blogs would never give you relevant backlinks but ya of course you can drive a good amount of traffic.