The contest in progress already has it's tone/identity and major
mid contest format changes against the original idea are always bad, imo.
Yes, there is tactical voting happening. It's cool.
Yes, several players got surprisingly many votes as most people like them and gave their 2nd or 3rd vote to them, despite not calling them their MOST favorite player (Haas f.i.).
Nadal and Murray have been eliminated already due to this special format.
And Federer maybe won't have such an easy time in the final either.
That's what makes this contest interesting and unique.
A mid contest format change will make something half-assed out of it.
That said, the ideas in the OP are interesting.
I would appreciate any separate contest(s) featuring some of them.
(There is plenty of time during the off-season.)
I am going to apply the format that wins this poll. I have only chosen to continue this contest, but I am not going to host such contests in the future ever again.