As far as the Edge stock the "worth" is in the assessment of the holder.
I'm sure the rifle would have a more quality feel to it.
Can't say as to weight savings.
Haven't heard of A7 stock induced wandering point of aim's.
Sometimes you have to say screw the worth and scratch that itch.
A Edge won't be worse.
Don't know about the rings either.
A7 has Weaver type base built right in doesn't it?
Does your scope have the length to not need that rearward extension?
If so get some Burris Signature ZEE rings.
I would go with mediums as the lows are LOW and even mediums low as most makers low.
Personally I like a little height in the ring/base combo and think lowest possible mounting over rated and harder to get behind shooting prone or uphill angles.
