General Principles of making risotto I made risotto for the first time last sunday - thanks to the advice I got from the posts here and here. I came to know about risotto from this site (probably not the correct way to learn about the recipe, as the questions in this site deal with particular aspect of the recipe of a food item thus expecting you to know the recipe ahead).

It was good (well, I have never eaten risotto before, so can't really compare) to my taste. There were so many recipies for risotto. Some call for wine, some do not have wine. Some call for juice, others for vinegar, some say no need to add anything beyond stock, etc...

I basically made vegetable stock, then fried rice in olive oil and added this stock to it slowly, ladle by ladle, over 30 minutes. At the end I added a mixture of fried vegetables to this cooked rice. The recipe tasted good. However I don't know what I am missing.

So my question what are the general principles when making a risotto? For what purpose is each ingredient (not the individual ones but generalised like stock, wine, juice etc...) added and when is it added? 

The only thing I am sure about is that I can fry any variety of vegetables and add them to the rice at the end.
The important part of making risotto is that you're moving it around in a little bit of liquid, so you end up scraping of the outside of the rice, causing the loose starch to thicken the remaining liquid to a creamy consistency.  The overall dish should be creamy but not mushy, with the individual grains of rice still having some firmness to them.

As for your specific questions :

For details on preparation, see https://cooking.stackexchange.com/a/137/67 .

Most ingredients are simply for flavor.  The acids (wine or vinegar) change how starch cooks and can keep it from getting too mushy, and add some brightness to the dish, but aren't absolutely necessary.