I've applied for the latest intake too but haven't been invited to a wombat.
For the training repayments, well it's over 7 years so you'd need $6285 a year taken for the actual loan only. I can't be bothered working out the interest but a rough estimate would be about $700 average a year? Of course income tax would be coming out too and would amount to another $7000 assuming you don't get a tax deduction for the training costs. The take home pay would end up being around $500 a week - about the same as a shop assistant.
Anyone know if the cadetship is a Government recognised course? It might be possible to get Austudy payments from Centrelink.