Do they get any sort of allowance or pay? For instance, per show or per song, etc.

I doubt it... but they get most things for free during their time on the show.

That's true, plus free accomodation..

I think they get the union minimum fee since they're performing on telly, like the BB lot.

Yes - the judges get about £1m each and they are on about £3 an hour.

Sickening really!

Why? The contestants have no bills or anything to pay. They are essentially living free and get to live a celebrity lifestyle for a few weeks.

Yes they do.. I recall somebody posting the numbers. Not earth shattering but a nice wee sum as theyre unable to work for months because of the show time potential etc.

They get expenses. I.e whatever their rent/mortgage/council tax etc x factor reimburse them since they're not working

In 2010 they were getting £30 per week IIRC and those with commitments like mortgages had those paid. But I remember reading at the time that Matt Cardle's dad said that Matt had asked to borrow money from him to pay his phone bill - so I don't think it can cover stuff like that.

Those that make it to the tour get paid reasonably well from that - I am sure £50K per song they got was quoted for the 2010 lot. As all of them had at least 2 songs each, that was £100K minimum and Matt and 1D got 5 songs so they got £250K. So if they make it to the tour, then the pittance they get on the show is worth it.