1) yes, you can invoke SysInspector with the following hotkey:
Control + LeftAlt + Numpad 0
Note that removing tasks might render the system unstable due to missing memory protection in AmigaOS.
Btw. the hotkeys can be edited in DOpus, press right-mouse button on empty desktop area -> Settings -> Hotkeys...
2) If you want to create shortcut on your desktop, press the right-mouse button over the icon you want to place on desktop permanently and select Leave Out.
With regards to the grid align, there's no any according to my knowledge. But you can align them by pressing right-mouse button on empty desktop area -> Icons -> Clean up. Note that the position won't be saved until you Snapshot the icons (pressing the right-mouse over the individual icon -> Snapshot, or you can snapshot all of them at once by pressing the right-mouse button on empty desktop area -> Icons -> Snapshot -> Snapshot all).
3) With these icons you can run appropriate Windows application. The screen will be switched to Windows and the application will be run. Note that this might not work on all systems.