Does the amount of undaunted rep for doing an initial dungeon achievement, such as the speed run, no death, glorious scroll, etc, correspond to the amount of exp in the quest journal under achievements?
No, Undaunted rep can be checked on the skills menu. This site has the reputation gains for delves, dungeons, and achievements listed: http://en.uesp.net/wiki/Online:Undaunted
I can't answer this with 100% accuracy, but I believe all the extra achievements (like speed runs, HM, no death) all grant 10 undaunted XP. So, if you do a Vet dungeon for the first time and get all those achievements, you'll receive 40 undaunted XP (get 10 for the first Vet clear as well I believe).