The surface grinder can be used for sharpening cutting tools but end mills is not really one of the jobs for it.
I use a surfacer to clean up and finish the parts used to be used in tooling for stamp press. With a good machine you can hold .0001" and better.
The magnetic chuck is usually never removed. It is ground flat to the machine the first time it is installed and then maintained flat after that. I see that you have some white wheels. That is good, they burn less than the cheap grinding wheels on a normal grinder, but they are soft and have to be sharpened fairly often with a diamond. When you place your work on the chuck, it is suggested to place a sheet of paper in between the chuck and the part to protect the chuck from wear and tear. How often this happens is very rare in the shops I have been in.
BTW the grinding dust that comes off the machine will go everywhere!! A dust collection system is a must.
Recently I made a new compound top slide, it is discussed in another post on this site. I used the surface grinder to bring the top parallel with the bottom of the slide and finish the surface as I wanted.
I would do a little research and playing with the machine. You may not have much use for this machine but others may.