As far as the acceleration - I'm going to get have to get my head around this more. E.g The speed you were travelling at when you started accelerating at has no bearing on the magnitude of the accleration, only the difference between the initial and final speed. However, the uncertainty in the initial speed will have an effect if the uncertainty has changed by the time you reach the final speed.
From the GIA corection website you linked:
"Major conclusions from tide gauge data have been that global sea level has risen approximately 10-25 cm during the past century."
A large range, but which equates to beween 1 and 2.5 mm/year/century, much more than the wiki.
