Tier 5 - Youth Mobility Visa - from Japan

I'm a British citizen who moved to Australia a couple years ago and I met my Japanese girlfriend in Australia. She is on a study visa in Australia, which expires next year when she will have to return to Japan. In the next year or so, I would like to return to the UK and she can hopefully join on a Tier 5 YMV. My issue is trying to figure out the timing of events.

Our two options are:
a) When her study visa in Australia expires, she obtains an Australian working holiday visa (for which there is no cap on applicants from Japan) and can come back to Australia for another 12 months
b) She applies for a Tier 5 YMV for the UK and joins the Japanese lottery to hopefully be selected as one of the 1,000 applicants approved each year from Japan.

Questions I'm searching the answers for and cannot find anywhere on the internet are:

1. How many Japanese people put their name in the hat each year and, therefore, what her odds would be of being approved per application?
2. Do Japanese applicants have to email the specific address in the specific window or can they just apply like other nations using the UK Gov websites?
3. If she is selected as one of the lucky 1,000, but we then decide to stay in Australia longer, does this harm future applications? (Note that my understanding is that entering your name in the draw is not the same as applying for the visa).

The ideal situation, I think, would be that she can apply every 6 months to see if she is selected to apply for a Tier 5 YMV as one of the 1,000. If approved, we can then make a decision as to whether we want to stay in Australia longer and apply again in six months time. The alternative is to take the opportunity to head back to the UK because we might have to wait a long time for another chance at being selected.

Any help would be much appreciated - as a British citizen and a 4 year work visa in Australia, my end is pretty flexible.