random questions

[Tyro]

In the options under controls there is auto target Alt-A and under game there is an option called auto aim, can't seem to find out what these do.

Also anti tank infantry don't seem to want to shoot tanks, I had one standing almost beside a tank and he did nothing, I orderd him to shoot and he just stood there and got killed, is there some command I am missing?

[kane1]

This has happened to me with that unit as well as other units but not all the time, also when I tell him to attack a Tank he'll run up a throw a AT nade. I know you can't do this all the time but it's best to DC him.

[Tyro]

Is there anyone that knows the answer to the first question about controls?