I'm in favor of initially limiting downvotes as a better way to prevent spam votes without discouraging people from voting on actually bad posts, though a single threshold for unlimited downvoting as a user privilege is probably more intuitive (for new users, and for PM to make) than gradually earning more.
Not sure the other changes are needed... Usually new users' bad posts are breaking a rule and should be removed anyway, and the simpler solution is probably just to have an appropriate number of staff to respond than to create a new system to go easy on bad posts. Basically, just do the promotions that were already supposed to be done...
For the last suggestion, I don't think privileged users should have extra sway over community concensus and mods are already able to check votes in case of foul play. If a post is unhelpful but doesn't break the rules (e.g., unviable moveset), it's more useful if someone comments explaining why and allows others to form their own opinion.