The "junipers" look to be something like Chamaecyparis pisifera 'Boulevard' with "dead brown junk" being a typical feature of the interiors of juvenile foliage forms such as this. With 4' tall being a lot smaller than kinds like this are genetically programmed to grow.

Try cutting the trees off level with the ground and leaving the remains to rot naturally beneath a concealing mulch. If replacement with different plants is part of the plan you might be able to plant between the cypress root crowns without digging them out.

Otherwise this says Spectracide Stump Remover Granules need only 4-6 weeks to work:

https://www.spectracide.com/Products/Disease-And-Fungus-Control/Plant-Disease-Fungus-Control/Spectracide-Stump-Remover.aspx

When you are ready to plant visit local retailers and see what they have that appeals. In USDA 7 you should be able to plant cold hardy stock in fall, which is preferable to spring or summer planting. Of course, the selection will be reduced in fall - but you might still find something suitable anyway.

The Spectracide product is only potassium nitrate, aka salt peter, which is what 99% of stump remover products have as an active ingredient. IME, it will take far longer than 4-6 weeks - longer than even 4-6 months - before the stump is broken down enough to make removal easy.

Planting in that same area is going to be a challenge unless or until the stumps and associated roots have been satisfactorily removed or decomposed.

There is a chance they were planted too close to the house. A lot of people do that.

You may be able to leave the stumps and plant something else in front of them.

I would also remove the round shrubs that black the porch.