The fell is the sewn part of the pleats. on any trad kilt it should be the same distance from your natural waist to the bottom, but can vary from the waist up depending on the rise the kiltmaker puts into it. The drop is typically from waist to bottom of kilt. The unsewn part of the pleats is called the unsewn part of the pleats, i guess. It sounds right that the unsewn part should be the same length from kit to kilt for a given drop.

I'd agree with the folks above - If you can wear it with the rise as is and have it near top of knee, keep it as is. If you do decide to get it shortened, Have it done at the to so you don't have ot mess with a hem, which would mess up the look of the MBP, IMO.