[ Serious actual work on really advanced drives should be going on, not just theoretical work and damn sure no more crap like the ISS. ]
Yes need to work on Heim Drives and gravity manipulation type devices.
Anything that can decouple an object from inertia will be a goo thing to research.
Yep, agree on that.
No matter how fast the drive, if you can't accelerate at a decent speed, you ain't going nowhere fast :^)