They all look like good changes. My only comment is that taking three years to implement is unnecessary.
I would suggest the following amendment – We elect three members this fall to 1,2 and 3 year slots. As their terms expire, all future terms are three years. Then, transition after one full year (November 2021). This would ensure that the three new members have a year to learn from the past PRs any needed knowledge transfer. It might be a bit extra work to manage the election this fall but it could be done by assigning the candidate who garnered the most votes to the 3 year term, second # of votes earned to the 2 year term, etc.