20 laps of a St James park means quite hilly for a major marathon. Take the WR off the table for sure, just look forward to some head to head racing.
Not at all. A quick look on Strava and it will end up around 450ft of elevation gain which I think is less than Berlin. It won't be a WR just because of the circumstances but the course itself is good for a time trial
This is assuming that they run the wide roads around the outside of the park. If they run inside the park it would be a bit more up and down. But I can't see that happening as all of the paths inside the park are too narrow unless the race is literally only Kipchoge and Bekele - you can walk only three abreast on the main path that cuts diagonally across the park, but all the others are narrower.
So I guess they'll run outside the park keeping the finish line on The Mall