I find that Iggies have a more nervous disposition and have heard of some major housetraining issues within the breed. And, frankly, a large person with a tiny and extremely fragile dog is probably not the easiest match to make. An IG could work, but I just got the impression that a slightly larger, more stable dog would be better.
Whippets like walks and runs, and our running to them is just a brisk walk.
IMO they need off-lead exercise periodically in order to really run.