You may take a journey to scandinavia, here you would be able to see similar harbours of the vikings on dry land.
Isostatic rebound is a highly complex movement. All places which had a significant ice load will rise, that is fast land today and it is shelf in front of Scotland and norwegian coast for example. So a part of the sea floor will rise too, but deeper down, the sea floor will descend as a reaction to the rising land and shelf.
The mantle under depressed crust will move lateral and lift up the sea floor when the crust is loaded, and when it is unloaded the movement will reverse.
Further you have to take local tectonic circumstances into account.
Look at the Netherlands and northern Germany. These regions had a significant ice load, but nevertheless are sinking today. This is due to much higher Ice load of Scandinavia and thus much higher isostatic rebound, AND, a reaction to the rise of the alps, tipping the whole plate. So, between to regions of uplift one region reacts with depression, despite it should be lifting too.
As i understand it, isostatic rebound of deglaciated areas will not add significant to sea level rise, because this effect is counteracted by deepening of the communicating areas of oceanic crust.
Regarding Flade Isblink, do you mean this study?http://onlinelibrary.wiley.com/doi/10.1029/2011JF001972/pdf
Here it is very difficult to distinguish between isostatic rebound of the crust and simple ablation of ice. measuring crustal uplift only with help of satelites is very difficult if you do not have fixed GPS stations at place, not on the ice but on rock.
Isostatic rebound is able to rise the crust with several cm/year. Your appraisal of several hundred meters is correct. When you calculate with a general density of ice of round 0,9 Kg/dm3 and rock 2,65 Kg/dm3 you will get an isostatic rebound of around 1000 m, very unaccurate, because of regional differences (and because 2,65 is only valid for upper crust rocks). How long it will take depends on the viscosity of the mantle local underneath the crust.
Please read : http://onlinelibrary.wiley.com/doi/10.1029/2001JB000400/full
for isostatic rebound in Scandinavia