if it dont fit in the hole with all 4 teeth, you could grind 3 teeth off the tool, so its a single tooth tool, that would allow you to move off centerline of the hole and it might fit then. if you dont know what i am referring to, look at the image below, i removed 3 teeth on that right side tool and it will fit into a smaller hole now you can see in this example image below so basically we could move the tool off centerline of the hole, plunge into the hole, then move back to centerline and do the toolpath, then move back off center before retracting out. note: if you do this you might need to add something like an M19 to orientate the spindle prior to entry/exit of the hole, and the tool itself in the holder would need to be orientated properly to ensure its going to align with the hole on entry since your pic shows little clearance for the size of that radii.

I build our computers and I can tell you that Mastercam just doesn't utilize the GPU or CPU, it is often only 10-15% uitilized. Compare that with gaming or rendering which use 100% of both at times. Solidworks utilizes much better but still not 100%. It is something they really need to work on, the quadro cards vs gaming cards make no difference. I put a GTX 1080 head to head with an M4000, enabling both in the nvidia control panel etc and set to use max power etc. multithreading enabled in Mastercam etc. It simply doesn't matter. One area that does make a difference is the clock speed of your cpu, running 5Ghz definitely calculates toolpaths faster then 3Ghz. So for Mastercam an expensive gpu doesn't really matter, but a i9 9900k is the best CPU for performance due to single threaded utilization of Mcam.

Yes, that is correct, it's currently only for the CIMCO Machine Simulation product, but will eventually support CIMCO Edit also If you have a CIMCO Edit Pro license, you can use it for Backplot in CIMCO Machine Simulation, which include 5-axis solid simulation and importing Fixture, Workpiece, Tools and Holders

You need to right click on the operation navigate to Edit selected operations and use the Change NC File Name and then you will get a new program posted for that group you pick. What I suspected when I read the topic you're not using Mastercam to it fullest.

I do this all the time with one machine group and may have 20 operations for one part. WCS helps and many ways to organized and keep your work tidy. I make each operation and main group and then make sub groups in that operation group. Here is one I am currently working on: Here is my planes manager.