1: languages do update, there are sometimes new things in it but their not always something you need to worry about too much.
2: http://www.w3schools.com is a great place to learn HTML, CSS, Javascript and other web programming languages all those can be typed in notepad, but other programs exist which can help speed the process up, Dreamweaver is a good one but you could find free ones around the web.
I bought myself the biggest book I could find on HTML4 (about 12 years ago) to learn from and that taught me everything about creating pages and uploading to servers etc.
3: HTML is the start, because all web pages are written using it, even if a site is coded in PHP it needs to output HTML in order to work in a web browser.
Once you have learnt a bit about web page development you could move onto Java which is used for web pages and phone apps as well as games.
4: Very
5: HTML is the language, CSS is slightly different but is embedded within HTML, and so is javascript but that is used to give pages more functionality and some kind of dynamic content, AJAX is a mix of HTML & javascript which you'll no doubt look into later on.
Moving on from HTML you would maybe want to look at learning PHP & mySQL to make sites with less 'static' pages.
6: I learnt HTML, moved onto PHP soon after and also dabbled a bit with Flash animation. since then I've done all sorts of stuff, 3D, graphic design, c++ and a lot I've forgotten about :)
The adventure never ends with coding :p