Hi there and welcome to WB Radenau!
If your blog is just a personal blog and you aren't concerned about making money then I suppose you could have all 3 subjects on one blog. If you think about it, that's how blogs used to look. They were just personal journals that covered a bunch of topics.
However, let's say you do decide to get more serious about it and make money. It might be a lot of work to split your blog into 3 different ones so perhaps it's best to segment now before you begin. And if you're looking to get search engine traffic from your blog, it's really best to keep your themes related.
Remember, even though these are 3 subjects you are interested in, what is the likelihood of your visitors wanting to read about all the topics. I remember reading about a full-time blogger (can't remember who) that started out with multiple topics. As the readership grew, the people who weren't interested in some of the topics would get mad when he would post on certain subjects. So he decided to create separate blogs that focus on one theme rather than having multiple unrelated topics on one blog.
As far as citing material, if you take something word for word (a definition for example) from someone's site then you should provide a link to their blog or cite them somewhere. There really is no set rule, but it's just common courtesy. I wasn't sure if you were talking about taking small snippets or entire paragraphs. For search engine (and ethical) purposes, you shouldn't copy anything word for word but if there's a small statistic you want to quote then it's a good practice to link to the blog and give the author credit.
|