Geoffrey Moore covers this in Crossing the Chasm [1]. He basically suggests that you have to specialize in an industry vertical to get beyond the early adopters and into the masses. Once you cross enough verticals, then you can come back and be a more general product.

I've also heard YAGNI [2] shouted at generalizations. People can spend too much time generalizing problems for broader application that never comes. I don't know the right answer here, as it seems hard to measure how likely it will be that any generalization will be reused later. Perhaps it's ultimately judgment.

[1] http://www.amazon.com/Crossing-Chasm-Marketing-Disruptive-Ma...

[2] http://en.wikipedia.org/wiki/You_aren't_gonna_need_it

To answer #1, three books I would consider must-reads are:

Crossing the Chasm by Geoffrey Moore He discusses the Technology Adoption Lifecycle and hi-tech marketing. http://www.amazon.com/Crossing-Chasm-Geoffrey-Moore/dp/00605...

The Innovator's Dilemma by Clayton Christensen This Harvard business professor discusses what makes a disruptive innovation. http://www.amazon.com/Innovators-Dilemma-Revolutionary-Busin...

Guerrilla Marketing by Jay Levinson He discusses some scrappy techniques for promoting your businesses. Not all are applicable to web or hi-tech companies, but it can still spark some great ideas. http://www.amazon.com/Guerrilla-Marketing-4th-Inexpensive-St...