There is no gurantee of what i will say.. but i think it will help a lot! At least i guess a lot of people do this..
of course it doesn't hurt your ranking. why would it? it's natural to link to your own blog, and google tends not to punish things that webmasters would naturally do.
Yeah it doesn't hurt it. Although placing too many links to your own site wouldnt be too good. Also if your going to be placing links to the same site, please use Anchor Text, it helps.
Yeah it's guaranteed at least to in-links to some of your own webpages is good for your PR. Thank You