would the new North Stand actually reduce capacity in any way?

Would be nice to have a capacity of around 22K If the new South Stand had an increase in capacity of 2K then I think there would be more chance of filling that more regularly (certainly against the big sides, or a resurgent Bradford). I think Leeds can average close to 16K home fans per game this season without too many problems of the back of last year. Especially if we get off to a good start. Success in the WCC would add a few hundred onto it as well.

Right to Light is not my field, but you are probably right. I think recent legislation requires neighbours to register their right to light more immediately or make compensation far more available as an option to developers to pay.
I am reminded of the new stand at Bradford City. There were neighbours' objections to that, but it was approved. The scale of the new build in relation to the original & the adjacent terraced building is staggering.

Anyway whatever if they mean what they say about completed by 2019 they are going have to get a move on

Will the south stand be seating or a terrace? If they do build the new SS with a different style of roof to what we have now and make it all seating a lot of the atmosphere will be lost. Look at the DW stadium that's all seating and there is no atmosphere there hardly, although that might be down to them having fans.

The DW's main occupiers are Wigan Athletic though so their was no chance for them to have a standing stand. Look at a out and out RL ground like Warrington and they have standing in the 'new-ish' stadium so I'm sure they'd keep the South Stand as a standing stand.

The original plans had two tiers, the upper one had seating & hospitality boxes if I recollect rightly.
Those plans were rejected by the council for being too high.
The revised plans showed an all standing new stand.