Okay, question 1: Yes, you can link to your blog but be careful. You can only link to your own external site twice (unless that changed) in a single hub or it will be considered self promotion and you will get flagged. My recommendation would be to only put one link in your hub to the blog, probably at the end of the hub. And you can link to each of the sites you are writing on in your hubber profile. I would definitely recommend that.
Q 2: I would definitely make all of your hubs full length. Don't do half a hub and then link to another place. Not only might that irritate readers by having to go on an easter egg hunt for the article, but HP won;t like the hub quality that will come of that, either.
Q 3: No, I wouldn't abandon the blog. If nothing else, just leave what's up there already alone and let it gain readers. You have done too much work (IMO) to abandon it. You can copy/paste all of your articles from the blog to HP and then delete them from the blog before you publish here if you want them all to be in the same place but be careful because it takes a little while for the blog posts to no longer be indexed by google. Until that happens, you are at risk of being flagged by HP for posting duplicate content. I'm not sure of the amount of time it takes for that to happen but I think it may be a few days. I know there have been forum posts about it so you can just do a search on here for the question.
I hope that helps! :)