bloody hell that was quick work !
As far as the g29 business goes - it just made no sense. And when I entered the 'figures' nothing changed.

Plus with the heated bed I've got height adjuster bolts round the edge, so it wasn't a problem. I'm used to bed levelling by instinct :-)

As far as the cooling fan goes - mine doesn't 'need' it.
But it'll give sharper prints and better bridging.

My 0.4 nozzle was fine. I just like the idea of the 0.5 more :-)
Much speed and fastness of printing !!!
And the reason mine didn't extrude initially was because it needed a ptfe tube in the hotend.

That's a good idea using the limit stop instead of the pressure pad. I can think of a couple better ways to mount it :-) Should only need one small bolt, which I've got.
I'll wait to mess with that once I've done the cooling duct.
Great idea to use it for levelling though !
I ignore the math and just adjust the height bolts till I get the same result from all three points on g29. Bed levelled.