T8s, instant start, and e-ballasts - looking for enlightment

Hi folks,

Having read what has been written on this topic I am thoroughly confused  
(which is not hard to do however). I am aware that this topic has been 
beaten to death on the list but I hoping all you experts out there will 
indulge me because I remain in the dark in this area.

My problem is that here in Australia nearly all flouro tubes sold happen 
to be T8 size and rated at 18W, 36W etc. It is nearly impossible to find 
a T12 bulb though I have seen a few at specialized lighting places.

This leads to my questions

1) Do the 18W and 36W power ratings mean that these tubes are not the 
high efficieny tubes referred to on the list rated at 17W and 32W. If 
these tubes are not the high efficiency tubes then what are they?

2) I've read in the archives that only e-ballasts can drives T8s 
properly. I doubt that this is the case here in Australia as it is near 
impossible to find e-ballasts and the only ballasts available are these 
big heavy things which don't look very electronic to me. (But then again 
- I've never seen an electronic ballast.) Am I right in believing that  
magnetic ballasts can drive T8's (at least in Australia)?

3) And finally I heard someone mention that e-ballasts designed for a 
4' tube shouldn't be used to drive 2' tubes even thought they might work. 
Is this so, and why?

James Wong