Hello dude , ( or dudette?) . Excellent work locating the various sites used as LOTR locations. This belated response concerns , the placing of the Helm's Deep marker . Are you quite certain of it's accuracy ? I'm pretty sure the actual quarry in question is a mile or so south of your placemark. (There are actually 2 quarry sites just south of your marker . I refer to the larger more southernmost of the 2 , the one with the clearly defined step levels) . I have studied still shots from a " making of the movie" DVD which match the layout of the afformentioned site exactly.
On another note , i have recently added a placemark of my own which may be of interest to your goodself . It marks the location of the house ( Gear House colonial homestead ) used extensively in P Jackson's first movie , Bad Taste. It can be found on the Eastern side of Porirura bay directly NorthEast of the quarry site.

Cheers ,

MoZrOb. (uk.)