Question #2:
Would a "regular" negative peak detector ciruit, like shown he

http://www.elektroda.net/cir/index/D...CTOR.htmgative


work for the DC Wave described?

That is not a "regular" peak detector, it is a comparator used as an
overcompensated opamp follower and exploits the open collector output
characteristic of fast discharge and slow ( 10 second) charge of the
capacitor. In concept it will work for a varying "DC sine wave" by
replacing "-Vcc" with "GND" and all "GND"'s with "+15V" in that circuit
diagram only. Then Vout= "Vpk,neg" =+5V.