Re: what's the need for this ?
There are some good reasons for electronic voting done right (most aren't).
* Detection of vote tampering
* removal of accidental donkey voting where someone changed their mind and started crossing things out rather than getting a new paper making their intention unclear
* immediate results where the numbers are close.
* sensible sized ballot paper. Our legislation limits the size and therefore with enough candidates you have real accessibility problems with readable font size.
* random order per vote so column 1 isn't hugely advantaged by donkey vote.
* Logistics in producing, transporting, storing, counting those papers.
These are not theoretical problems. In the recent election, Western Australia's senate race was very close. Last and second last at specific points were within automatic recount thresholds at numerous points and preference flows varies the overall winner. During the recount they could not find from memory about 1000 votes from one polling station. They did simulations of both possible flows and demonstrated that the result could change which in the end cost many millions of dollars in a state wide revote.
In answer to your other question. Poll booth attendance is compulsory. What you do our don't write on your ballot paper is up to you but it will be considered informal if you don't fill it out correctly (wink wink nudge nudge). Compulsory attendance is actually a good thing (hasn't always been my view). But it achieves some useful effects.
* providing a mandate to the parliament (note parliament != government).
* much harder for anyone to use stand over tactics to keep opposing populations away.
* moderates the nuts that exist at the frays of all ends of the spectrum. I know that a number of places where politics doesn't seem to be contesting ideas but rather trying to motivate half interested parties to bother to turn up. If everyone is already there, you need to focus on how your policies affect the whole constituency or you won't get a large sway.
The real amazing part is that for once the parliament seems to have thought through the problems that such a change opens up, where good intentions have unintended bad consequences. If only they now apply their newfound wisdom to the slippery slopes of days retention and media reporting of special operations,I, for one would be much happier.