how do you add a single vertex to an edge in blender?
select the verts on either side of the edge, hit w and select subdivide.
to add a single (freestanding) vert, ctrl-LMB (if a vert is selected when this is done an edge is created between them).
yup just be careful if it’s already got a face along the edge otherwise it will put your vertex there and also split your face into 3 with a big triangle somehwere. when that is going to happen to me I usually delete the face, add the vertices I need and hit F while selecting 3 or 4 vertices and make a new face so I don’t get the annoying triangles all over.