Hi, and welcome. I'll try to help out. First, the number is a reputation score. It is different from the amount of steem power you have. Higher is better, and it's on a logarithmic scale, which means it's easier to go from 20 to 30 than it is from 30 to 40, and so on. You increase (or decrease) your reputation score by getting upvotes or downvotes from people. People with high reputation scores and steem power can affect your reputation score more than those with low steem power or low reputations. This is a way to filter spam content. The reason those comments have disappeared is probably because they were from spam accounts, and with the new reputation score they are being hidden.

On steemit.com, there are posts and comments. Comments are replies to posts and do not show up in the main feed. A blog is kind of just a common term for a place where someone regularly posts. You might consider your personal website a blog if you regularly post things there. You might also consider steemit.com to be a place where you blog (it can also be a verb).

In order for someone to find and follow you, all they need is your username "vicuturuslibertas". You can directly lookup any user by just typing https://steemit.com/@username
Hope that helps.