here are some cutoms i wanted to show

The easiest and most obvious way to make a motorised Neil that's not scratch built would be to repaint Samson (like GBHtrain's version). Not quite as good as a scratch built one with the right wheelbase (which seems to be what you're going for), but it should still be effective. If he will have the extended funnel, it should end at the same point as Old Slow Coach's clerestory.

As wonderful as that H0 shed looks, it's just a little too small for TOMY despite being able to accommodate rolling stock on track. If not the obvious Hornby or Bachmann, it looks better suited for Take Along or another smaller system. You might want to raise it up by adding flat supports along the bottom.

Seeing the Take 'n Play controllers like this reminded me of what Leo did with STH from the blue car, except he just happened to find a perfectly sized figure and took the legs from it. If not separate legs, there should at least be a seam in the middle so they won't look like blocks. The legs themselves should be thinner at the sides (especially Percival's) and have actual feet, the grey should be lighter and the coats need to be finished off with some more black. Optionally, the arms could've been removed and replaced with new ones to make them poseable if needed.