I can comment on the flak vest and leave the more precise measurements for the armor plates to someone else.
That looks like a MoW vest and in it's current state it is not 501st approvable.
It needs to "close down the back" according the 501st CRL.
I recently brought up the same question on the Bounty Hunter Guild forums. I ended up selling my MoW vest and getting one from Arkady.