Well, it all depends. I personally use just a regular text pad editor (
http://www.editplus.com), but it's up to you. A lot of new editors just tell you what to do, but I personally think you gain more from knowing it and become more efficient this way too.
As far as what type of HTML standard to use, I would XHTML for the sheer fact it is recommended, the newest and most up to date, and it is more standard across websites now a days as well. You will find it's not too much different than regular HTML 4.
For CSS rules, it's totally up to you. It depends on how elaborate you want your coloring scheme to be really. If you are only going to use a couple colors, then you use the rules in various blocks around your site. So, I can't really tell you how many you will have as it's dependent on the amount of content and various blocks on each page.
Just like any new person starting web design, I would create a website, and if you run into problems, try and work your way through it and then ask for help. It's always better for yourself to see if you can get through it first!