It looks like your source recording frame rate is 23.976, so you would probably want to change the TV standard to NTSC and output frame rate to 23.976 as well.

Unless you were changing the original speed of the clip, you can leave time interpolation blank. Otherwise optical flow is fine.

CBR bitrate encoding just means that you are using a constant bit rate for each from of video, which isn't really necessary, depending on how fast your machine is, you'll achieve very similar quality with smaller file sizes if you change it VBR 2 pass.

For h.264 Shutterstock does ask for "best" encode quality, which would probably mean 300mbps, but unless you were recording RAW files with an Inspire 1, that is a higher original bit-rate than your source footage, so it's overkill and just going to lead larger file sizes. If this was a Phantom 3 or 4, you can set the target bit rate to 200mbps and that would be plenty high.

Square pixels and progressive field order are both correct.