How Many km could I expect to get from the above per tank ?

Have a read
http://www.aussieveedubbers.com/forum/viewthread.php?tid=4503 
http://www.aussieveedubbers.com/forum/viewthread.php?tid=2876 
And to answer your next questions:
http://www.aussieveedubbers.com/forum/viewthread.php?tid=2489 
http://www.aussieveedubbers.com/forum/viewthread.php?tid=2128 
http://www.aussieveedubbers.com/forum/viewthread.php?tid=4039 

:thumb