Yes to No.1 ; since the AGM's are sealed there is no danger to the Controller for corrosion or Ofgassing and sparks so no problem. But the compartment should be sealed well enough from the elements because controllers are not rated for outside use. (danger to moisture, rain, dust, road-salts etc.)
Unsure to No.2 ; I am not sure about Newmar's EMS spec's but I do have the Progressive EMS LCHW-50 and I believe they are very similar.
Very Sure to No.3 ; We recently installed a super modern Swedish "Separett" Compost Toilet and so far we like it, it looks very stylish (unlike the other model they carry YOMD) and it is "plumbed in" on the wet side, meaning to the grey tank, of which we now have 2 (again unlike the other model they cary) and this saves us having to empty the pee container every few days (3-4) now we only have to haul out the dry waste once every 4 to 6 weeks when used by two adults continuous.
Like I said we only installed it this early spring and have used it since but so far we are happy with it, the one 12v (computer)fan that ventilates and dries the poo does a good job keeping the smell from entering the bathroom never mind the Coach! There is of coarse a direct vent from the toilet to the outside driven by this fan which runs continuous, IT JUST WORKS!
No more Black tank boogers.