When is it that the public votes only count as there are only three in final
Will Len dance with Zoe in final ?

They may not bother now because the way they've changed the judges scoring since the Tom debacle I think the public fave can escape the dance off from the bottom of the leaderboard, even in the Semi, if the judges use ties (as they did in Toms year) it will just make it easier for the judges least fave/public fave to escape instead of harder. Hence how Chris Hollins made the 3 person final. No probs.

With there now being a three couple final rather than four will that make the running time less or will the couples have to perform three dances each before the elimination leaving the final dance off for the viewers votes for the final two couples?

I don't think they had a dance off in the semi-final in Chris's year as they said something about the public should be allowed to have the finalists they wanted. There were only two people in the final that year as Ally Bastion was eliminated on the combined judges' scores and public vote.

That explains it then: if there were only 3 in the semi final, because the public fave is more likely to end up in the d/o in that case if the judges gave comes second.

This year there will be a 3 person final so the public fave should get through even if they are bottom with the judges.

The deciding points will be the quarter finals and semi finals

QF & SF would need to have no tied scores.

J + P =
5 + 2 = 7
4 + 3 = 7
3 + 4 = 7
2 + 1 = 3} Dance off
1 + 5 = 6} Dance off

Yes but that's a very specific permutation and as discussed ties would make it even easier. With both QF and SF it is more likely the public fave gets through than doesn't.

I personally am in favour of dumping the D/o from QF onwards but I can't imagine them doing so because it's highly unlikely the public fave would land in the dance off and it certainly isn't definite like the situation with Tom