Getting to Know Them--You're Characters, That Is

A question for all you fiction writers out there: How do you develop your characters? Do they pop up in your head and just start talking to you? And, more importantly, do you talk back? Do you develop an extensive personality profile for each of your main characters? Do you run them through a Myers-Briggs Personality Test to determine if your hero is an ISTJ or an ENFP?
I 'm reading Building Believable Characters by Marc McCutcheon. McCutcheon promises that if you use his book "you, too, can create characters who think, hope, love, cry, cause and feel pain, save the day--and seize readers by the emotions."
Wow.
Impressed me--and I'm a nonfiction writer.
The book contains a "Character Questionnaire." You're supposed to fill it out before you start writing your story. If I filled in all these blanks about Characteristic Gestures, Areas of Expertise, Short-term and Long-term Needs, Prejudices, and Most Painful Things in One's Life, I'd know my hero better than I know my best friend!
I'm a bit of a thesaurus junkie, so I devoured the "Character Thesaurus." Lists and lists and lists to help you describe the people in your novel. Complexions. Noses. Body types. Bad habits. Occupations. Words to describe fear, suspicion love, laughs.
How about these for love:

• gaze at candidly
• exchange predatory looks--works for me if you're an elk
• eyes dark and smoldering
• regard provocatively
• exchange scorching looks
• stare adoringly
• regard with open fondness
• beam fondly

Okay, okay ... you get the idea.

Any other suggestions for creating believable characters in your novel?