Hold down the amiga key and use the arrows to move the mouse pointer. Can't remember what click is, just try some key combos and you will get it.
It's Amiga+LeftAlt for a left click and Amiga+RightAlt for a right click.
Hold down Shift to make the pointer move faster.
And provided you've got some way of hooking a C64 disk drive to your Amiga, you can probably rip disk images. Not sure what program to use, but there's probably something on Aminet.
