Under the new legislation, the strata manager would only be allowed to hold one proxy, as would you.
It will get interesting if only you and the strata manager (with one proxy) turn up at the AGM. You would have equal votes (unless his proxy has a higher Unit Entitlement.
The message is clear – make sure you always have your one permitted proxy in your pocket, then you can always outvote the strata manager.
The answer to question 1 is moot since the strata manager can only carry one proxy. However, if that proxy carried more Unit Entitlements than opposing votes (collectively) then they could pass any motion except those regarding their own contracts.