In the first few diagrams, I added because without something like that, attacking is not necessarily the best plan for black. I'm aware that there's some room for debate on this point (and maybe you especially wanted to show how white makes a base), so I don't mind if you put it back the way it was before, it's just a suggestion.
I left that black stone out because I could see some sequence like the following being playable in a game in some circumstances-- and also to point out that touching a stone out in the open (which beginners do) is very, very bad.
Bill's comment has me looking for a better example. I think I'll put it back until I or someone finds one-- the footnote I put at the bottom doesn't make sense with in place already ;)
Thanks for your additions and interest! :)