Here's a good explanation for R/W: http://www.fangraphs.com/library/misc/war/converting-runs-to-wins/
WAR does not use OBP and SLG. WAR uses an amalgamated version of the stat, wOBA, which is outlined in the description to bring it down to one offensive number. So if that HR hitter had the same wOBA as the high OBP guy, it would have no impact on the lineup, and if it was higher, the lineup would be better, etc. So, yes, you could say that WAR adjusts for that.