You don't need peat on the bottom for them, just peat soaked water, but they are egg eater so a trap of one type or another is advised.
Marbles or gravel is fine for the Danio's.
It can be hard to see the eggs if they spawn in the middle of the tank, I would suggest placing the spawning moss or mops next to the glass so you can see the eggs below the marbles.
Neons - no, it is hit and miss, if the fish spawn but the eggs are dead, condition them again and spawn - neon that are not compatible will not spawn at all.
Just use large and lots of mops for the Widows, that worked really well for me. set them up to breed on the week end so you can remove the pair once they have finished spawning to avoid eggs being eaten. Use pairs.
The male can only pay attention to one female at a time and the other one will be eating eggs.
One month to condition the for mentioned fish is twice as long as it should take - they can breed every 2 weeks - if feed right.