Need Help selecting a barrel...............

[Christopher67]

Ok im pretty sure I've finally decided on a barrel, its either going to be one of these 2.

http://jtdistributing.com/16-6-5-grendel...sight.html


&


http://jtdistributing.com/20-6-5-grendel...w-fsb.html


Bolt face depth I'm told from a rep is. "It is 0.136."

I have 3 questions:
1.Both barrels are 1/9 twist, is this acceptable?

2.Would 2-3" moa at 200yds be unreasonable or would i be expecting to much out of a "rack" grade barrel?

3. Is POI going to be that much of a difference going from a 16" to a 20" barrel?