I once saw a documentary on the way roses were grown in a municipal rose garden in Montreal (USDA zone 5 or 4) The method they used was to cut all roses to the ground in late fall, including climbers. They did not, however, say how they thinned out the new growth when the roses resprouted in spring.
I do think that some Osmocote 15-15-15 might be good. ZD has a lot of growing to do and it will need some fresh nitrogen. Also, keep the rose well watered as it is putting out new growth. With my own ZD rose, I tend to prune too conservatively and the the plant ends up getting shrubby rather than climbing. My guess is that you will want to reduce the number of canes somewhat to achieve greater height.