1)Can a single complex script replace all events?
Generally, no. Python can access objects, but not all features are available through python yet (eg. behaviors). This is why I state Construct is an event-based tool, the event features are mature, and the python features are still "beta".
[quote:1nacvv14]2)What are the limits of what the script can do? Can it call new sprites into being? Load new resources into the game?
You can create objects, and you can use the script versions of the event actions which load resources from files.
[quote:1nacvv14]Will it allow you to use C code (I found a wonderful bitmask pixel-perfect collision detection library that even reports the coords of the impact)?
No, that's something completely different, although you can use C++ in the Plugin SDK and make a new object. By the way, Construct has an MMX-accelerated pixel perfect rotatable bit mask collisions engine, and I don't know of any faster engine. I'd be interested to know which engine you're talking about because if it's faster/better, I can think about improving Construct's collision engine. Also, normally it is not possible to accurately report the co-ordinates of an impact since a collision usually involves one or many regions of overlap, and even just taking a simple average causes the collision engine to be slower, because it can't stop as soon as it finds one case of an overlapping pixel.
There's nothing in your game spec that can't be done. You just have to put in the work hours to make it.