Need some approximate measurements but at first glance, it doesn't look like you have much room to add the plants you mention - columnar yews get very wide in time and will easily block your windows and just based on the guesstimated size of the already planted boxwoods (and my own landscape design background), space is a major issue and you will have trouble squeezing in the other shrubs as well. And it would be helpful to know the sunlight/shade conditions of this planting area. Even north facing gardens will receive a lot of light in summer so not sure this is the best spot for hostas.

Sorry about missing that "shade garden" part in your subject line :-)) But my comment still stands - that does not look to be a very shady location. Like I said previously, even a north facing garden gets a huge amount of indirect light unless under a broad overhang or other sky-obstructing item. At most, I'd consider only part shade plants.