timm back in the day gps was a bugger due to the off set. todays units, be it in the boat or hand held will do the job quite nicely.
In reference to dropping structure. You want to place the structure in locations that will hold fish for that time of year. Winter locations will be out in the deeper part of the lake where summer and fall will be shallower. If you have a map of the lake try to find irregular features...drops, points humps ect. More than likely the fish are already using these location during certain times of the year and you are wanting to just spice them up with cover to give them a better holding area...basically put them where you want them within that area.
When you do your drop mark the location on GPS, I sometimes use a marker..drop my structure then that will insure I get a good GPS location. Then pull your marker and go do the next one.
When it's time to fish I move toward the waypoint into the wind. Just before I get to it I stop and make cast, the wind will keep you from running over it if it's in shallow water and bumping the TM will put you back in place. On my deeper structure I will run over the waypoint to see if it's holding fish. If it is I toss a marker to the right of the boat (away from the structure but inline) to use as a reference and then use a bottom bounce rig or heaver jig to work the structure.
Save your money on the camera and get a GPS unit, they can be had for less than a camera now a days and are far more valuable on the water. I have both and know which one I would get rid of if I had too.
Hope this helps ya out and let us know how it goes...good luck