Dave, be cautious about the shops, some are unscrupulous in selling things as civil war artifacts.
As for Killer Angels its an excellent choice for Grasping the battle.
For the Gettysburg movie I can be seen about 5 different areas of the Triangular field/ 124 NY Orange blossoms (when you see a blur of a soldiers head run by the camera you can see the Silver Lozenge diamond on my bummer) helping a wounded soldier off the field, firing over stone wall, and probably 2 bodies dead on field. Also the Color Guard of the 99th PA retreating down the Rocks of Devils den into the Valley of death, one on wall one behind in background. My musket still bears the scars of slipping andfalling off that boulder during one of the filmings.
The slaughterpen is between little round top and the den to the left. The accounts of 8th NJ in wheat field are excellent. So many amazing stories. 12th NJ at high water mark. 2nd, 5th, 8th Floridas on the counter/follow on attack of Picketts charge.
Hard to walk those grounds knowing the stories. A must have book is John Batchelders papers on the Battle, pricey but must have research.