Hi, thanks for making this. I'm pretty sure that I manage to catch all of the comments and posts scattered about (even though I don't respond to most of them), but a centralized location could be handy.
Why do you want to define custom routes for your units? The pathfinding should be finding the fastest route, already, and it will occasionally need to recalculate the route on the fly (if the path is blocked, for example).
This has come up a few times. It's more feasible in 2.0 than it was in 1.4, but still quite a major undertaking for a one-person operation. I won't rule it out, but it's also not currently planned.