Hey! First time writing on scioly! I have been apart of the high school team for 3 years and I have done my fair share of building events (6 I think). So I decided to give my 2 cents.
Electric vehicle: I liked the ability to reverse, but make sure you specify how long the track has to be to run the event. This year I saw tons of vehicles crash into the wall because they went to 12 meters then tried to reverse when the track was only 10 meters.
I personally really like the idea of an obstacle course. However, I do not want to make it where teams who can't program couldn't enter. Therefore, I would suggest the weaving course should be optional as a bonus.
As for the weave course, try and think outside the box. I think doing something other than a bucket would be fun!
Robot arm: I very much disliked that you couldn't take items out of the competition area and they wouldn't be counted for points. I felt constrained by my personal ability to maneuver the robot arm. I had a master-slave system and I would knock a couple pencils out of bounds sometimes because the out of bounds tape was so close to the pencil erasers. Or I would accidentally just tap an egg carton with a ping pong ball out of bounds. Consider making the competition area larger, but do NOT make the robots have to reach further. If you make the cartons further away teams would have to spend more money on more expensive parts. Keep the max reach distance at its current distance.
As for the actual objective of robot arm. I think you should make it so teams can't possibly get everything done in the allotted time. Make a ridiculous amount of objects you have to pick up, rotate, roll and cut time down to the point where teams cannot do everything. Also consider allowing teams to do 2 runs because I know I felt I was hurt my human error controlling the robot. And maybe make it so we can program the arm to do certain tasks (make the rules very specific about the placement of all items)?
Finally for robot arm. Please, make the rules very specific about passive and active end effectors. Can we drop them outside the competition area? Can we drop them in the competition area? Is tape allowed? Are magnets allowed?
I felt this year's rules were much better than last year. Mission possible was a mess in 2015. I appreciate the double effort to make SO a better competition for everyone so we can learn and bask in the awesome of science!