Yes, that would be handy to be able to just paste in a route as you say for example "ROCKI DBL J60 BCE GRNPA". In the meantime you can only "Open" FS9 and FSX .PLNs.
IF pulls all the waypoints from the actual scenery you are running. If you install scenery that changes the waypoints, VORs, NDBs, runway numbers, directions, and magvars then that would be the data IF uses.
Plans for the upgrade mean you will be able to install Navigraph or other similar data sets which overlay the data pulled from the sim, of course the aircraft would have to have the same dataset loaded in the FMS since it would be different to the sim.
SID/STARS is like choosing the runways beforehand, IF does that as it is handy for accurate ETA and FUEL on short routes, if you get the runways assigned (or are not usng ATC).
Your input is very much appreciated. I'll post here when I have more to say. I'm in discussion with Navigraph and there are other sources introducing waypoint data in the near future.
All the best