So, if I'm reading this correctly, the necessary bandwidth for standard AM
will be twice the audio bandwidth, which must be between a minimum audio
bandwidth of 4000 Hz and a maximum audio bandwidth of 10,000Hz.



Contrary to popular belief, AM stations broadcast with a bandwidth of
20KHz, which
makes for audio up to 10KHz. This much bandwidth in a tuner works well
for local stations,
but for DX work you'd want to cut your bandwidth in your receiver to
+-5KHz to avoid
excessive splatter. Even then, you'll still get some "monkey chatter"
from an adjacent channel
station. "Monkey chatter" is a technical term for the modulated audio
that came from station
A showing up "upside down" when you are listening to station B, 10KHz
away on the dial.
"Upside down" meaning that an audio tone of 9KHz station A transmitted
gets demodulated
by your radio when it's tuned to station B, as a 1Khz tone. 9.5Khz -
500Hz, and so on.
Human speach "inverted" this way sounds like "monkey chatter". The only
way to reduce
monkey chatter is to null out station A with the loop antenna. But if
there's another station C
10KHz on the other side of the desired station, and not in the same
direction of the first
undesired station, you're sunk.

You'll also want a sharp 10KHz notch filter (9Khz in Europe and
Australia and elsewhere).
That's to get rid of the heterodyne from the adjacent stations' carriers.

If you can find a copy of RDH4 (Radio Designer's Handbook edition 4), it has
lots of info on radio receiver design. But it assumes that you have a
working
knowledge of electrical engineering. That is, not a beginner's book.