Welcome. It sounds like you've come to the right place to continue building on your existing accomplishments and portfolio. I think it's fine to repost your own original content. Others may disagree, but as long as it's your content, it should be fine.
As for your other question, yes, all topics are open for exploration, especially if your purpose is to explore them and not be concerned about the rewards that you get. Not all topic are as popular as others, but if they interest you, they will probably interest others as well.
I appreciate the advice. I was thinking re-posting my original content would be ok but thought I'd ask the community first. I'll always try to update and add unique twists to it just for people who follow me on Steem.
This can be a good place to network and advertise your other blogs, but I think adding updates and unique features, like you said, is a good idea.