How come your sequence is HDV 1080i as opposed to HDV 1080p24?
GoPro still images typically have a huge resolution. To create the timelapse use QT 7 Pro. File > Open Image Sequence , select the first image in the folder, choose 24 fps since that’s what your project is, than wait for QT to build the timelapse. Then File > Export, export a 1920 x 1080 ProRes with Preserve Aspect Ratio set to Crop, which will allow the image to fill a 16×9 frame.
You can use MPEG Streamclip to render out the GoPro .mp4’s to ProRes.