I can appreciate your passion for learning this topics! Unfortunately, your questions are ones that can have rather long-winded (read: book length) answers. Let's take one question as an example.
The how-to of persona creating is still up for debate. It's a bit more of an art than a science at this point, but at the very least should be based on analytics gathered from your web application.
Here's an example of some of the debate going on within the industry. Usability.gov has some great standards on the subject. The standards suggest, among other things, include providing a persona with an age and gender. There are some industry leaders that believe in removing age and gender from personas. The argument they provide is that these facets of a user don't provide relevant context, and only add assumptions. On a certain level, that makes sense.
There are others (myself included) that believe the usefulness of a persona is two-fold. Not only does a persona allow you to synthesize data captured from analytics into usable format, but they also allow for designers to design for an actual human being rather than the generalized "user" that is so often discussed around the conference table. Removing aspects such as age and gender only serve to de-personify the persona, which seems a bit of a contradiction of terms.
I'd also argue that age and gender play important roles in certain types of websites and interactions. The age range of your demographic should affect your design, especially if you're designing for older audiences. There's a significant amount of research and knowledge behind understanding how older adults interact with the web.
Also, there's an element of difference when it comes to usability as it pertains to genders. Women notice and use different aspects of a UI than men. There's also empirical evidence that things such as font choice may have a large effect on how men and women consume user interfaces.
While it may be politically correct to have the concept that "women are no different from men," the reality of the situations, when it comes to UX at least, is that there's a distinct difference.
I only write all of this as a way of giving an example of some of the intricacies that are involved. There's a great font of knowledge when it comes to creating user personas, but you're likely going to have spend some time reading up and google searching articles to get a good feel for it. I recommend starting off with the usability.gov page linked above, and going from there.
If anyone else has some good resources for our friend here, I'd love to see them!
EDIT: I took this post and ran with it for my blog post for today.