[Leica] R4, 6, 7...what's the difference?

[bruce5@attglobal.net]

Is a R7 @ $1,200 more or less desirable than a R4 @ $550 assuming both
are in excellent  condition?  I know the 7 must have more
features/benefits than the 4 due to development, but I don't know the
particulars.

I'm getting the camera for my wife, who takes mostly
kids/street/landscape, and would like the option of going auto from time
to time...so unfortunately an M is out.

Finally, do you think there's a better lens to start with than a 50/2?

Any facts/opinions/thoughts would be greatly appreciated

Thanks,
Bruce