Traditionally, telecined footage comes with a 3:2 pulldown to accommodate the 24fps it was shot in with a 29.97fps workflow. If your EX footage was shot at 24, and the 35mm was as well, make sure to request it at 23.98fps without pulldown.
As for video format, 1920×1080 ProRes HQ is probably best if they can do it. You could go 2K or 4K if you wanted to (and their machine could handle it), but since you’re working mostly with EX, you might as well have it match.