I would say you are likely the most common type of gamer. So I would say most have similar experiences.
3. Am I a realistic demographic that RPG companies are currently targeting, and why or why not?
As been said before, it is hard to know what companies target. But I would say you are one of the demographics they target. I imagine most target more than one.
4. How does the "hard core" demographic affect what the RPG companies do to try and bring in new players and the products they produce?
Well like any company the things that sell the best will influence what they make in the future. So i would say the typical gamer is actually more likely to influence things. Since they don't buy everything or most things like the hard core gamers do. But on the flip side, most hard core gamers are GM's and they tend to influence their gaming groups buying habits by influencing what is used or not used in games.
5. If I want to continue to play and enjoy the hobby, what should a person in my position do to promote it, considering that I look on the "FLGS experience" with a high level of distaste?
Introduce new people to the hobby in a positive way and encourage them to take part. Encourage others to do the same. New people is good for everyone, companies and fans. Then also buy anything you like for your game or better more than one game to help the industry grow.
6. If people like me are now more regularly the "mainstream" of RPG players (which may not even be a valid assumption), is it unrealistic to expect that there will be a sudden "Renaissance" of teen and twentysomething players, given RPGs' challenges as an entertainment medium? Can companies promote products that appeal to both the uninitiated, as well as the "hard core"?
Maybe, but I honestly doubt it. Unless some company takes advantage of technology and figures out a way to make RPG games look like and be online like a MMO, yet still play like a more typical table top game. If that happens then i think we will see a big upswing again. Until then I think we will have ebbs and flows but nothing major until that happens or the current generation of gamers get to old to play. Aka in retirement homes and can't remember where their dice are anymore