Re: The 5-string question (versus 4 string)
I don't believe this is accurate. At the end of the day I think it's more about personal preference than anything else. Saying something like 5 strings are for bassists but 4 strings are for guitarists using bass to record is just blind stereotyping instead of stating a preference. There are many, many great bassists who play and prefer 4 string basses and there are plenty of guitarists who prefer a 5 string bass.
This. It's a personal preference. Many great (well known) bassists use(d*) 4 string basses primarily.
Geddy Lee, Marcus Miller, Jeff Berlin, Jack Bruce* Stanley Clarke, Pino Palladino, Billy Sheehan, Geezer Butler, Jaco Pastorius*, Flea, Larry Graham, etc.
Not to forget, the bass is modeled after the upright bass which is a 4 string instrument.
A person should play what they prefer. I would not want to be stuck with my 5 string as a primary bass instrument. Others might like having that tonal range always at their finger tips. I have one 5 string, but vastly prefer the thinner necks of my 4 string basses. It feels easier and faster to get around, and more ergonomic. A trade off I usually prefer. It's simpler and I like the B string being out of my way when not needing it. I'll use the 5 string only when called for or in the mood for it.
Instead of down tunings, its a great alternative, or use it with some of the harder styles.