There are so much blog in this world. Millions I guess.
a lot
No, but at Wordpress you can tell how many people read your blog and where they're from.
Since blog is a pretty new word, there is none in Spanish (yet). You can use blog and people would understand, however.
Anyone can write the blog because blog is one type of information based on the particular topic, which will help people in many terms but if you write blog make sure that blog should be informative and helpful for people.
A blog title is the blog's name e.g. "No stupid answers". A blog address is the web address (URL) that people need to use in order to get to the blog via web browser e.g. http://nostupidanswers.com
The most popular travel blog online would be Travel Today. This blog has many different people that write for it and is read by millions of people daily.
People who like to blog can be called blooks, if that is the nickname that someone wants to use for them. However, they would likely prefer to be called writers.
There are lots because most people in US have internet connection.
People blog for fun keeping in contact sharing photos and events.
You do not have to do anything. Usually it is enough to register your blog and you will get an address in a form of e.g. blablabla.blogspot.com You give this address to your readers and they can use it to access it.
tags are keywords by which you can describe the content in the article / blog post you write. These can be keywords which people use to search, mis spellings, alternate spellings etc.,
Blog has its URL and keywords. It can be used to trace up your blog in the internet.