I have been questioned by the FAA (never NTSB) on two occasions. One was impromtu, the other was by appointment. No attorney was present, nor even thought of, but I never have been knocked out in a plane crash and didn't know what happened.
The first time was flying my Cessna 177 from Hayward, California to Orange County, California, when the alternator went out. First, the transponder stopped, then the radios (I had a back up battery powered radio). So, ATC had a heads up of a problem before I landed. I was met on the ramp at my plane by FSDO dudes (the FAA guys that handle this, Flight Standards District Office). EDIT: They may have been GADO in those days, General Aviation District Office.
One side note. I was an FAA employee at the time, in ATC. Anyhoo, these guys were all business, which gave me the initial impression that they were jerks. But, they asked for my pilot certificate, and medical. Asked a few questions. Never heard from them again. No problems.
On the second instance, I had some problems with control of my Beech Baron, after a new paint job. I declared an emergency, and landed. The FSDO was notified by me, and they came out and took a look. Very pleasant dude.
Virtually all the FSDO guys/girls are pilots also.
For you book, any reader would not be surprised that in the USA, you don't fart without calling a lawyer. But, it could just as easily not be a factor.
But, if I thought I had done something wrong, you bet I'd get a lawyer who specialized in this type of investigation. But without a lawyer, just like with a police man stopping you for a road side chat, you hand him your license, don't admit to jack squat, and don't volunteer information that can be used against you. If it progresses beyond questions and a traffic ticket, sure, get a lawyer. The same would go for a car crash.
As to the NTSB, they do not investigate ever plane crash. Plane running out of gas and crashing.... yawn. They've heard that story a few times. I doubt they'd make more than a phone call. NTSB for aviation is a really tiny office in Washington DC. FSDO's are everywhere.
I, too, wouldn't buy that a single fuel pump caused any plane to crash.