Hi,
It varies.
You can breed them all year round it seems.
In my case it is probably because of the climate here in Scotland but mine always seem to lay later in the year.
I wouldn't build mine the way I did the first time but there are loads of plans in the DIY and caging forums. I was worried about not being able to get the right temps so built in extra space for lights and other junk I didn't need.
If I replace it the new one could be as much as a foot narrower and 6 inches shallower.
Here is the thread with pictures of the monstrosity.
And here is the colubrid rack I built using the wood from the old 5 foot ball python vivarium.
Pretty much yes.
Two males are more of a problem but seperate really does seem to work out better.
dr del