Polmont grade-separation wasn't part of the original EGIP. At most, NR had the idea of moving the station westwards in the Route Study so that each line would have its own set of platforms but that wasn't taken forward. Grade-separation there may well be feasible but the incremental value of doing it once Greenhill and the Almond/Dalmeny chord are done is probably not that great. Bottlenecks are never great but they're often perfectly manageable so long as there aren't multiple bottlenecks interfering with one another. Once the other works are done the junction at Polmont can be a more important factor in timetabling.
Haymarket West will be improved when the chord is built. After that, it looks doubtful that significant extra capacity can really be found through Haymarket without an even larger intervention. The big flaw with the 'semi-reasonable' HSR suggestions is that you can't just dump trains onto the WCML at Slateford and call it a day, since they'll then just cause problems at Haymarket instead. There really won't be a lot of point investing cash in new tracks for Edinburgh to Glasgow services if they'll still slow to a crawl at the eastern end, and the number of new trains is heavily constrained.