3d graphics renderer math

I need assistance with completing 3D graphics render code for data plots written in C++. The code takes a list of 3D primitives, lines, spheres, text, etc, and displays these as 3D objects.
The code works; it can display 3D primitive shapes correctly using orthographic projection or projective transform. But there are some remaining issues with the matrix math:
1. View volume is calculated to enclose the view space plus 50%, but when translated to NDC using a scale+translate matrix, some Z vertices are outside the [-1, 1] NDC clip region. Objects inside the view volume in view space should map to inside NDC space after viewspace to NDC matrix transform.
2. Rotating the camera, strafing left/right, in/out do not work correctly. Also I need a zoom control to shrink the view volume around a region of interest. I need smooth intuitive mouse controls for navigating 3D space.
3. Algorithm for scaling objects (text, sphere) for depth needs improvement. Want some combination of size and color saturation to indicate relative object distance.
I am looking for someone with experience with linear algebra for gaming or 3D visualization to help with the math for my 3D graphics renderer.