A. Lagging is generally not over analyzed, so it is generaly pretty conservative. One or two holes won't effect much. Often lagging has utlity penetrations in unforseen locations, which generally does not cause a problem. Probably would be good to keep holes & penetrations out of the middle third if possible.
B. Since lagging is only stacked, it is generally self draining. Some locations, straw is suffed between the boards to prevent migration of fines. Generally weep holes are not needed in lagging.
