On thing I can think to remove the aliasing is set the motion quality for FAST. As odd as it seems, this fixes all the aliasing issues I have when clips are resized in fcp. Sometimes though the aliasing goes away further if you render out your timeline. The viewer will not show this improvement until you render out a completely separate file.
Everything else sounds right, make your timeline the same size/codec as the majority of your mixed footage is to ease the pain during the process.
as for color correction, I would render out the timeline to ProRes or uncompressed to keep image degradation to a minimum.