Interesting questions Jason. People here can help you and you might find additional help down below in the Software and Hardware forums. Try those too.
Let me try:
Do you mean number of bits per memory address? Those bits are transmitted from RAM to CPU via a data bus consisting of individual electric lines on the circuit board. Switching from 8 to 16 makes designing the boards more complicated.
I assume you mean memory address register? Or instruction register as I see it. RAM is accessed in bytes: one address for each byte. How many bits does it take to write 500,000 in base 2?
Same dif: What's the largest number you can write with 6 bits? 20 bits?
BNF? you got me dude . . .