In order.
The implications are that the EBC is bleeding more air than it would have if the acutator did it first. As long the increase is within the range of operation of the EBC it wont be a problem. In practice, it shouldn't matter, and that is generally why most people don't uprate their wastegate actuators.
Im not familiar with your turbo install, so I couldn't tell you if you could or couldn't install a new actuator in situ.
The variables would be:
- difference in size of new anad existing actuator (may be the same?)
- space around existing actuator and if this would allow removal and install
- time to fiddle within said space to do the replacement
- time to take turbos off and replace actuators and the replace turbos.
You'd have to weigh up each option based on those (and some other variables, like what tools you might have available) and make a decision.