Besides the provided accessories, the main difference is the M5s option attaches with both the MIL-STD 1913, Picatinny.
The Aimpoint CompM5s Red Dot Reflex Sight has an 18mm clear aperture size.
Unfortunately, currently there is not an option to buy the Aimpoint CompM5s Red Dot Reflex Sight without the mount.
The Aimpoint CompM5s Red Dot Reflex Sight would be a great optic for the LWRCI IC-A5. The Aimpoint CompM5s Red Dot Reflex Sight mounts to picatinny rail so you will not need any other mount.
The Aimpoint TwistMount, part number 12234, and the Spacer, part number 12227.
TwistMount - https://www.opticsplanet.com/aimpoint-twistmount-ring-and-base-complete.html
Spacer - https://www.opticsplanet.com/aimpoint-ar15-spacer-qrp-and-twistmount-ring.html
Yes, you will be able to co-witness your iron sights with the provided mount.
Yes, you will be able to co-witness your iron sights.
Yes, the Comp M5 models will use standard Aimpoint Micro compatible mounts.
According to Aimpoint, the standard configuration of the CompM5s contains the sight, an LRP mount and a spacer which gives 39 mm optical axis.
According to Aimpoint, it ships with the mount in the first picture on the left.