What do most people do?
I for one will always look at the gcode at the beginning and end of the program to confirm the tool pathing is correct.
Don't care what program generated the code or how I may have input the settings.
Under Clearance Plane in Cambam if default is chosen as a setting, then it is to a safe Z location before a rapid to a new location.
That takes care of a collision. But as noted leaves you with a slow movement for some distance.
In some programs you can also define at what postion of the Z travel the cutting will start to occur. So you would have a rapid to some point
above the surface and and then a different feedrate there after into the material. If not available, one could add it to the code if the CAM dosen't provide for it.
A manual code entry would seem very reasonable if the code is used manny times as in your case.
You can set the start point in CamBam to say 1" above the face and have the clearance plane set at say .001 such that you will get a rapid (G0)
to a distance above the surface and then the slower feed rate will be applied for the plunge in. FWIW
Where i start or end depends on what i plan on doing afterwards, but most work done is a one of a kind. Sometimes it has to be done more than one time
and having the machine return to a chosen position is preffered. That position may be above or to the side of the material.
All is not just plug and play when one wants to do something specific.
RICH