This is a very well thought out and well written post, and highlights many of the issues I've felt with the server. For months now it's felt as if the quality of staff has been decreasing greatly, not all staff, just some of the people that came along didn't put as much effort in as they could.
Regarding your points:
1. I wholeheartedly agree, a "talking to" does next to nothing to most staff members, and rarely are punishments ever given to staff outside of a talking to. Upper staff needs to be more liberal with their punishments for the lower ranked staff members.
2. Yes, the MOTD is kinda a mess, and needs to be completely reworked, with feedback from the Super Admins.
3. I'd even argue that 16 is too young as well, it should be 17 or 18, it will greatly decrease the number of potential applicants, but will also weed out many individuals who simply aren't mature enough to run. I remember a staff member that was straight up 13, which baffles me.
4. I agree with this point quite a bit, but it could be potentially abused by angry players and the lot, sit doesn't go the way they want, they give a 1 star or whatever. This happened a lot when I was staff, however, I think implementing it is a good idea. Now that the community manager position is open again, it should be filled by a far more active player, and this should be one of their main jobs, is looking over evaluations and discussing them with the involved staff members.
5. This is good too, it's even more meaningful when it comes from upper staff like Admins and the like.
Furthermore, I'd like to add that there should be more interaction and involvement for higher staff positions, and they should be more strict in time given, for example, more slack should be provided for auto-demote times for Moderators, but more strict for S-Mods and higher, I get that people have lives, but these positions are not as common as the others, and are supposed to represent experience and overall good work, so why are they a rare sight on the server (or at least was when I was playing often) These positions should be taken only by people who are experienced enough to be considered, but also because they want to take the job to help more, not because of a rank change and "clout" or whatever, and they should be prepared for the more strict schedule the promotion provides. Overall, you've raised a fantastic point here, good work.