the thing is some versions of php4.x are not compatible with Zend, so they need to downgrade php and recompile it, not only installing zend. That is why they will do it on weekend, with low traffic, so they will not put offline some websites due to php recompilation, apache restarts, etc.
I think so
You can't use IonCube ? this can be installed by you without complications, if you need a fast solution.