1) not needed for a level 1 cert flight, or for that matter most flying. while it does add some durability for transport and handling it will not save the rocket if it lawn darts into mud.

2)I would first consider how much room the recovery system needs (chute, shock cord, eye bolts etc.) and mount it leaving enough room for the recovery Plus space for the coupler shoulder and evebolt (iirc about 3" for shoulder and eye bolt), this will keep the chute from sliding and changing the cg.

3) typical install is into the aft centering ring, forward button in a location that will not snag the chute or shock cord, forward centering ring usually works.

4)probably yes to both. hth,
Rex

Just to expand on RexR's answer:

3/ I like to put the upper button somewhere close to the CG, if possible.

4/ The small nylon screws are shear pins and are meant to break at ejection, allowing the parts to separate. Nylon rivets are for holding things together at ejection so the parts do not separate.

Well, just as a follow up, I got the rail mounts attached, got it finished, and used it to get my Level 1 Cert at Bong in July. I'm happy about that and about how it turned out, thanks for your help!