I want to share this great list of do-follow Lists: The 1000 Do-Follow Blogs/Social Networks/Forum/Website List [Updated] With tutorial on how you can make you blog to support do-follow: How to make blog do-follow then if you have one you can also join building the largest do follow blog list at SEO Do-follow List. Hopefully this helps.
Its up to you, may not approve spam comment. But from comment you could get good feedback from your audience.
Not really. With Askimet enabled is not suicide ... I run several blogs and I don't have any problem with spammers, only from time to time is necessary to clean the spam folder Also please check http://www.dofollow.us
My links have always been nofollow and I have used askimet since I started my main blog and always moderate comments. I still have 10-15 spam comments every day. Wouldn't you think my spam would increase drastically if I make the links dofollow? It's no problem to delete the spam but I have to read all comments to figure out which are legit and which ones are spam. That takes time.
Good sharing here, whether follow or nofollow may be good, it depend what they want to do with their website